Ossifying Fibroma in the Nasal Cavity of a 2-Year-Old Horse

animals

Case Report Ossifying Fibroma in the Nasal Cavity of a 2-Year-Old Horse

Bernard Turek 1,* , Kamil Górski 1, Olga Drewnowska 1, Roma Buczkowska 1, Natalia Kozłowska 1,* and Rafał Sapierzy ´nski 2

1 Department of Large Animals Diseases and Clinic, Institute of Veterinary Medicine, Warsaw University of Life Sciences (SGGW), Nowoursynowska 159, 02-776 Warsaw, Poland; [email protected] (K.G.); [email protected] (O.D.); [email protected] (R.B.) 2 Department of Pathology and Veterinary Diagnostic, Institute of Veterinary Medicine, Warsaw University of Life Sciences (SGGW), Nowoursynowska 159, 02-776 Warsaw, Poland; [email protected] * Correspondence: [email protected] (B.T.); [email protected] (N.K.); Tel.: +48-604-247-640 (B.T.)

Simple Summary: This article reports on the clinical features, diagnosis, and management of ossifying fibroma in the nasal cavity of a 2-year-old horse. Ossifying fibromas (OFs) are rare, benign, fibro-osseous neoplasms that occur more frequently in the rostral mandible of young horses (termed equine juvenile mandibular ossifying fibromas) but rarely in older horses. The occurrence of OF in young animals suggests developmental disorders or trauma as etiological factors. The local recurrence of OFs is common if they are not completely surgically excised, but metastatic spread is unusual. The presented case remained clinically asymptomatic until the mass obliterated the whole nasal cavity, causing severe breathing difficulties. The exact mass location was revealed using diagnostic images—namely, radiographs and computed tomography (CT) images. A concurrent problem of an underdeveloped and hypoplastic last premolar tooth of the maxilla was diagnosed. Because the mass was well-demarcated, the horse underwent standing surgery to remove the mass and the tooth. Histopathological diagnosis of ossifying fibroma was confirmed. The patient recovered uneventfully Citation: Turek, B.; Górski, K.; and remained free of disease at the 2-year postoperative follow-up. Drewnowska, O.; Buczkowska, R.; Kozłowska, N.; Sapierzyński,R. Abstract: A 2-year-old mare of an unknown breed was referred to the clinic due to undetermined Ossifying Fibroma in the Nasal breathing difficulties. Physical examination revealed painless swelling rostral to the nasoincisive Cavity of a 2-Year-Old Horse. Animals notch and a large, firm mass protruding from the left nostril. Radiographic examination of the head 2021, 11, 317. https://doi.org/ revealed a mass occupying the left nasal cavity and a displaced and hypoplastic last premolar of the 10.3390/ani11020317 left maxilla. The CT scan showed a well-demarcated heterogeneous mass measuring 22 × 9 × 5 cm

Academic Editor: Alessandro Spadari (length × height × width) in the left nasal cavity attached to the roots of the displaced tooth and Received: 23 November 2020 conchae. The surgery was performed on the standing horse. Firstly, due to the oblique position of the Accepted: 20 January 2021 displaced tooth, the extraction was performed extra-orally through the trephination and repulsion Published: 27 January 2021 of the maxillary bone. In the next step, a direct surgical approach was chosen for the caudal part of the mass via the osteotomy of the left nasal bone. The mass was bluntly separated from the conchae Publisher’s Note: MDPI stays neutral and removed through the nostril using Fergusson forceps. The histopathological characteristics of with regard to jurisdictional claims in the mass led to the diagnosis of ossifying fibroma. The horse recovered completely in seven months, published maps and institutional affil- without recurrence after two years. iations. Keywords: tumor; ossifying fibroma; tooth; extraction; computed tomography

Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. 1. Introduction This article is an open access article There are no clear-cut data on the incidence of tumors in the skeletal system in horses. distributed under the terms and Only in one paper was the rate of occurrence reported to be below 1.5% [1]. conditions of the Creative Commons Ossifying ﬁbromas (OFs) are ﬁbro-osseous neoplasms that most commonly occur on Attribution (CC BY) license (https:// the intramembranous bone of the skull and mandible [2] and rarely in the appendicular creativecommons.org/licenses/by/ 4.0/). skeleton [3]. Fibro-osseous lesions have been reported in humans [4,5] and a variety

Animals 2021, 11, 317. https://doi.org/10.3390/ani11020317 https://www.mdpi.com/journal/animals Animals 2021, 11, 317 2 of 11 Animals 2021, 11, x 2 of 12

of domestic animals, including dogs [6], cats [7], rabbits [8], llamas [9], birds [10], and ruminantsdomestic [animals,11–13]. including dogs [6], cats [7], rabbits [8], llamas [9], birds [10], and rumi- nantsIn horses,[11–13]. ossifying fibromas usually affect the rostral part of the mandible of young animalsIn agedhorses, between ossifying 2 and fibromas 15 months usually and affect are termedthe rostral equine part juvenileof the mandible mandibular of young os- sifyinganimals fibromas aged between (EJMOFs). 2 and These 15 months lesions and may are replace termed alveolar equine andjuvenile cortical mandibular bone, cause ossi- thefying loosening fibromas of the(EJMOFs). teeth, interfere These lesions with themay mastication replace alveolar of food, and and cortical predispose bone, cause the jaw the toloosening pathological of the fractures teeth, interfere [14]. Although with the the ma causestication of OFof food, is unknown, and predispose several hypothe-the jaw to sespathological have been suggested,fractures [14]. including Although developmental the cause of disorders OF is unknown, that may several affect ossification hypotheses athave a young been agesuggested, as well including as trauma developmental [15]. Other reports disorders have that described may affect OF ossification in horse max- at a illayoung [16], paranasalage as well and as trauma sphenopalatine [15]. Other sinuses reports [17 –have19], proximaldescribed tibia OF in [20 horse], and maxilla the fourth [16], metacarpalparanasal boneand sphenopalatine [21]. sinuses [17–19], proximal tibia [20], and the fourth meta- carpalOssifying bone [21]. fibromas tend to recur if they have not been completely removed, but metastaticOssifying spread fibromas is unusual tend [ 22to ].recur The if objective they have of not the been present completely paper isremoved, to describe but themet- clinical,astatic imaging,spread is andunusual pathological [22]. The findingsobjective of of an the ossifying present paper fibroma is to in describe the nasal the cavity clinical, of aimaging, horse. and pathological findings of an ossifying fibroma in the nasal cavity of a horse.

2.2. Materials Materials and and Methods Methods 2.1.2.1. Case Case Presentation Presentation AA 2-year-old 2-year-old mare mare of of an an unknown unknown breed breed was was admitted admitted to to the the clinic clinic due due to to breathing breathing difﬁculties. On initial examination, the general conditions of the patient were assessed difficulties. On initial examination, the general conditions of the patient were assessed as as poor because of malnutrition, poor quality of fur, and general neglect. Breathing was poor because of malnutrition, poor quality of fur, and general neglect. Breathing was strid- stridulous, with no passage of air through the left nostril. Temperature and pulse were ulous, with no passage of air through the left nostril. Temperature and pulse were within within normal limits. A deformation was visible on the left side of the head, rostral to the normal limits. A deformation was visible on the left side of the head, rostral to the naso- nasoincisive notch. Epiphora was noted in the left eye. During a detailed examination, a incisive notch. Epiphora was noted in the left eye. During a detailed examination, a firm, ﬁrm, non-shifting mass protruding from the left nostril was found (Figure1). non-shifting mass protruding from the left nostril was found (Figure 1).

Figure 1. Firm mass protruding from the left nasal cavity of a mare with breathing difficulties. Figure 1. Firm mass protruding from the left nasal cavity of a mare with breathing difﬁculties.

2.2.2.2. X-ray, X-ray, CT, CT, Endoscopy Endoscopy Examination Examination RadiographsRadiographs were were obtained obtained byby computedcomputed radiography (Gierth HF HF 80 80 Plus, Plus, Gierth Gierth X- X-rayray International, International, Germany, Germany, and ConsoleConsole AdvanceAdvance DR-IDDR-ID 300300 CL, CL, Fujiﬁlm Fujifilm Corporation, Corporation, Tokyo,Japan) Japan) with an with indirect an indirect conversion conversion system system for scanning. for scanning. The leftThe latero-lateral left latero-lateral (LL) and (LL)right and 30° right dorsal–left 30◦ dorsal–left ventral oblique ventral oblique(Rt30D-LeVO) (Rt30D-LeVO) projections projections were assessed. were assessed. A well-de- A well-delineated,lineated, oval-shaped, oval-shaped, and slightly and slightly heterogeneous heterogeneous mineral mineral opacity opacity was seen was within seen within the left thenasal left nasalpassage, passage, extending extending from fromthe level the level of 208 of 208to the to thenostril nostril (Figure (Figure 2a)2 a)[23]. [ 23 Triadan]. Triadan 208 208was was displaced displaced into into the the rostral rostral aspect aspect of the of the nasal nasal cavity. cavity. The The morphology morphology of tooth of tooth 208 208 was wasabnormal, abnormal, with with markedly markedly variable variable radiopacity radiopacity and and hypoplastic reserve,reserve, andand clinical clinical crown.crown. Deciduous Deciduous teeth teeth 607 607 and and 608 608 were were visible visible (Figure (Figure2b). 2b). The The right right and and left left maxillary maxillary sinusessinuses remained remained intact. intact. Animals 2021, 11, 317 3 of 11 Animals 2021, 11, x 3 of 12

(a) (b)

FigureFigure 2.2. (a) Radiographic examination inin latero-lateral projectionprojection demonstratingdemonstrating aa well-demarcatedwell-demarcated massmass withinwithin thethe nasalnasal cavitycavity (white(white arrows)arrows) and and displaced displaced Triadan Triadan 208 208 (black (black arrow). arrow). (b ()b Rt30D-LeVO) Rt30D-LeVO projection projection of of the the maxillary maxillary region region revealing reveal- hypoplasticing hypoplastic dislocated dislocated maxillary maxillary last premolarlast premolar (black (black arrow). arrow). Clearly Clearly visible visibl deciduouse deciduous Triadan Triadan 607 and 607 608 and (red 608 arrows). (red arrows). The endoscopic examination of the right nostril revealed the rightward bending of the nasalThe endoscopic septum; an examination of the leftright side nostril was revealed unavailable the duerightward to the presencebending ofof the mass.nasal septum; Computed an examination tomography of of the the left head side was was performed unavailable under due general to the presence anesthesia of inthe dorsal mass. recumbency.Computed tomography The patient of was the head sedated was with performed detomidine under (0.02 general mg/kg) anesthesia prior toin anestheticdorsal recumbency. induction The with patient diazepam was sedated (0.1 mg/kg) withand detomidine ketamine (0.02 (2.2 mg/kg) mg/kg). prior Anesthesia to anes- wasthetic maintained induction with using diazepam isoflurane (0.1 (induction mg/kg) and 5%, ketamine maintenance (2.2 2–3%).mg/kg). CT Anesthesia images were was acquiredmaintained with using a Revolution isoflurane 750 (induction CT scanner, 5%, GEmaintenance Healthcare 2–3%). Corporation, CT images Chicago, were acquired IL, USA (120with kV,a Revolution 280 mA, at 750 1.3 CT mm scanner, slice thickness). GE Health Two-dimensionalcare Corporation, tomographic Chicago, IL, sectionsUSA (120 were kV, viewed280 mA, using at 1.3 the mm RadiAnt slice thickness). DICOM 2020.2.3Two-dime software.nsional Multiplanartomographic image sections reconstructions were viewed allowedusing the for RadiAnt the identification DICOM 2020.2.3 of the software. exact location Multiplanar of the mass, image which reconstructions extended from allowed the levelfor the of identification Triadan 208 toof thethe rostralexact location part of of the the nasal mass, cavity. which The extended space-occupying from the level lesion of wasTriadan well 208 defined, to the heterogeneous,rostral part of the and nasal measured cavity. approximately The space-occupying 22 × 9 ×lesion5 cm was (length well ×defined,height heterogeneous,× width) with internaland measured zones ofapproximately calcification (Figure22 × 9 ×3 ).5 Thecm (length mass caused × height the × deformationwidth) with internal and compression zones of calcification of the left dorsal (Figure and 3). ventral The mass nasal caused conchae, the the deformation deviation ofand the compression nasal septum, of the and left the dorsal thickening and ventra of thel nasal right conchae, dorsal and the ventraldeviation nasal of the conchae nasal (Figureseptum,4a). and The the tooth thickening was displaced of the right palatally dorsal to and the nasalventral cavity, nasal and conchae the morphology (Figure 4a). was The abnormaltooth was duedisplaced to hypoplastic palatallyreserve, to the nasal clinical cavity, crown and and the roots, morphology enlarged was infundibula, abnormal anddue Animals 2021, 11, x variableto hypoplastic radiodensity. reserve,The clinical apex crown of 208 and was roots, deformed enlarged and infundibula, had a direct and connection variable4 of to radi-12 the

massodensity. (Figure The4 b).apex The of sinuses208 was appeared deformed normal. and had a direct connection to the mass (Figure 4b). The sinuses appeared normal.

Figure 3. Sagittal CT image obtained left to sagittal line (bone algorithm, WW1500, WL 300). The mass length × height are Figure 3. Sagittal CT image obtained left to sagittal line (bone algorithm, WW1500, WL 300). The mass length × height are indicated with green lines. Connection between the mass and the Triadan 208 is present (green arrow). indicated with green lines. Connection between the mass and the Triadan 208 is present (green arrow).

(a) (b) Figure 4. (a) Transverse CT image at the level of Triadan 07 (bone algorithm, WW1500, WL 300), demonstrating a heterogeneous mass obliterating the left nasal cavity (width × height—green lines). Note the rightward deviation of the nasal septum and thickened right dorsal and ventral nasal conchae (red arrows). Internal zones of calcification are present. (b) CT transverse plane at the level of Triadan 08 (bone algorithm, WW1500, WL 300). Note the relationship of the mass (white arrow) with the dental apex of Triadan 08 (red arrow).

2.3. Surgery Surgery was performed using the following steps: extraction of the deciduous teeth intra-orally, extraction of Triadan 208, and removal of the tumor. All procedures were performed in a standing position during the same anesthetic protocol. The horse was sedated using detomidine (0.02 mg/kg IV) and butorphanol (0.01 mg/kg IV), maintained with constant infusion rates for detomidine (0.02 mg/kg/h) and butorphanol (0.01 mg/kg/h) diluted in saline, delivered by an infusion pump. The dose was adjusted according to the horse’s behavior. Maxillary cheek teeth were anesthetized with a left infraorbital nerve block using 5 mL 2% lidocaine hydrochloride [24]. The left maxillary nerve was blocked caudally from the maxillary foramen with 20 mL of 2% lidocaine hydrochloride [25]. The horse was monitored with a vital sign monitor (ECG, pulse oximetry, capnography). The deciduous teeth 607 and 608 were removed intra-orally without any complications. Due to medial displacement and the oblique position of the Animals 2021, 11, x 4 of 12

Animals 2021, 11, 317 4 of 11

Figure 3. Sagittal CT image obtained left to sagittal line (bone algorithm, WW1500, WL 300). The mass length × height are indicated with green lines. Connection between the mass and the Triadan 208 is present (green arrow).

(a) (b)

Figure 4. (a()a )Transverse Transverse CT CT image image at the at thelevel level of Triadan of Triadan 07 (bone 07 (bone algorithm, algorithm, WW1500, WW1500, WL 300), WL demonstrating 300), demonstrating a hetero- a heterogeneousgeneous mass obliterating mass obliterating the left the nasal left nasalcavity cavity(width (width × heig×ht—greenheight—green lines). lines).Note the Note rightward the rightward deviation deviation of the ofnasal the septum and thickened right dorsal and ventral nasal conchae (red arrows). Internal zones of calcification are present. (b) nasal septum and thickened right dorsal and ventral nasal conchae (red arrows). Internal zones of calcification are present. CT transverse plane at the level of Triadan 08 (bone algorithm, WW1500, WL 300). Note the relationship of the mass (white (b) CT transverse plane at the level of Triadan 08 (bone algorithm, WW1500, WL 300). Note the relationship of the mass arrow) with the dental apex of Triadan 08 (red arrow). (white arrow) with the dental apex of Triadan 08 (red arrow). 2.3. Surgery 2.3. Surgery Surgery was performed using the following steps: extraction of the deciduous teeth intra-orally,Surgery extraction was performed of Triadan using 208, the followingand removal steps: of extractionthe tumor. of All the procedures deciduous teethwere performedintra-orally, in extraction a standing of position Triadan du 208,ring and the removalsame anesthetic of the tumor. protocol. All procedures were performedThe horse in a standingwas sedated position using during detomidine the same (0.02 anesthetic mg/kg protocol.IV) and butorphanol (0.01 The horse was sedated using detomidine (0.02 mg/kg IV) and butorphanol mg/kg IV), maintained with constant infusion rates for detomidine (0.02 mg/kg/h) and (0.01 mg/kg IV), maintained with constant infusion rates for detomidine (0.02 mg/kg/h) butorphanol (0.01 mg/kg/h) diluted in saline, delivered by an infusion pump. The dose and butorphanol (0.01 mg/kg/h) diluted in saline, delivered by an infusion pump. The was adjusted according to the horse’s behavior. Maxillary cheek teeth were anesthetized dose was adjusted according to the horse’s behavior. Maxillary cheek teeth were anes- with a left infraorbital nerve block using 5 mL 2% lidocaine hydrochloride [24]. The left thetized with a left infraorbital nerve block using 5 mL 2% lidocaine hydrochloride [24]. maxillary nerve was blocked caudally from the maxillary foramen with 20 mL of 2% lido- The left maxillary nerve was blocked caudally from the maxillary foramen with 20 mL of caine hydrochloride [25]. The horse was monitored with a vital sign monitor (ECG, pulse 2% lidocaine hydrochloride [25]. The horse was monitored with a vital sign monitor (ECG, oximetry, capnography). The deciduous teeth 607 and 608 were removed intra-orally pulse oximetry, capnography). The deciduous teeth 607 and 608 were removed intra-orally without any complications. Due to medial displacement and the oblique position of the without any complications. Due to medial displacement and the oblique position of the Triadan 208, it was impossible to grasp the crown with the molar forceps. An extra-oral technique was used that involved an approach to the roots through the left maxillary bone trephination and extraction by repulsion [26]. A 6 cm incision was made through the skin, and subcutaneous tissue levator nasolabialis and caninus muscles were bluntly separated. The periosteum was elevated and pushed off the bone. A 25 mm diameter trephine was used for creating a hole in the bone rostral and dorsal facial crest, below the infraorbital foramen. A disc of bone was removed to expose the roots. A dental punch of 10 mm size was used for the repulsion of the tooth into the mouth. During the surgery, the crown of the diseased tooth was palpated orally to detect vibrations and confirm the correct positioning of the dental punch. The tooth was subsequently removed in one piece using dental elevators. At the end of the surgery, a drain was placed in the wound. It was removed 3 days after surgery, and no complications in healing were observed. Pe- riosteum and subcutaneous tissue were closed using a simple continuous suture pattern (absorbable monofilament thread 1/0), and the skin was apposed with 8 widely spaced, simple-interrupted, non-absorbable sutures (monofilament thread 1/0). Animals 2021, 11, x 5 of 12

Triadan 208, it was impossible to grasp the crown with the molar forceps. An extra-oral technique was used that involved an approach to the roots through the left maxillary bone trephination and extraction by repulsion [26]. A 6 cm incision was made through the skin, and subcutaneous tissue levator nasolabialis and caninus muscles were bluntly separated. The periosteum was elevated and pushed off the bone. A 25 mm diameter trephine was used for creating a hole in the bone rostral and dorsal facial crest, below the infraorbital foramen. A disc of bone was removed to expose the roots. A dental punch of 10 mm size was used for the repulsion of the tooth into the mouth. During the surgery, the crown of the diseased tooth was palpated orally to detect vibrations and confirm the correct positioning of the dental punch. The tooth was subsequently removed in one piece using dental elevators. At the end of the surgery, a drain was placed in the wound. It was removed Animals 2021, 11, 317 3 days after surgery, and no complications in healing were observed. Periosteum and5 of sub- 11 cutaneous tissue were closed using a simple continuous suture pattern (absorbable monofilament thread 1/0), and the skin was apposed with 8 widely spaced, simple-interrupted, non-absorbable sutures (monofilament thread 1/0). ExtensiveExtensive damage damage to to the the apex apex of of the the alveolus alveolus created created an an oronasal oronasal ﬁstula fistula measuring measuring approximatelyapproximately 2 2 cmcm inin length by 1.5 1.5 cm cm in in width. width. In Inthe the initial initial treatment, treatment, lavage lavage and and deb- debridementridement were were performed. performed. In In the the next next step, step, surgical surgical gauze withwith iodoformiodoform was was immersed immersed inin a a semi-liquidsemi-liquid paste of of plaster plaster of of Paris Paris then then compressed compressed slightly slightly and andplaced placed in the in fistula the ﬁstula[27]. [27]. ToTo remove remove the the mass, mass, it it was was necessary necessary to to make make an an additional additional dorsal dorsal approach approach through through thethe osteotomy osteotomy of of the the nasal nasal bone bone to release to release the caudal the caudal connection connection between between the mass the and mass nasal and conchaenasal conchae [28]. After [28]. the After incision the incision of the skin of the (10 skin cm), (10 extending cm), extending to the subcutaneous to the subcutaneous tissues, blunttissues, dissection blunt dissection was used was to displace used to the displace levator the nasolabialis levator nasolabialis and levator and labii levator maxillaris labii muscles. The periosteum was elevated. An oscillating saw was used to create a rectangular maxillaris muscles. The periosteum was elevated. An oscillating saw was used to create a bone fragment measuring 2 × 5 cm caudally to the nasoincisive notch (Figure5). The rectangular bone fragment measuring 2 × 5 cm caudally to the nasoincisive notch (Figure removal of the bone allowed direct access to and inspection of the caudal part of the nasal 5). The removal of the bone allowed direct access to and inspection of the caudal part of mass, which had a pedunculated attachment and was adjacent to the dorsal and ventral the nasal mass, which had a pedunculated attachment and was adjacent to the dorsal and conchae. The connection was removed with a periosteum separator by blunt dissection. ventral conchae. The connection was removed with a periosteum separator by blunt dis- Minimal bleeding occurred. The mass was separated and extracted through the nostril section. Minimal bleeding occurred. The mass was separated and extracted through the using Fergusson forceps (Figure6). nostril using Fergusson forceps (Figure 6).

Figure 5. Intraoperative view. Dorsal approach to the caudal part of the tumor by the osteotomy of Animals 2021, 11, x Figure 5. Intraoperative view. Dorsal approach to the caudal part of the tumor by the osteotomy of6 aof 12 a 2 × 5 cm bone fragment dorsally to the infraorbital foramen. 2 × 5 cm bone fragment dorsally to the infraorbital foramen.

(a) (b)

FigureFigure 6. Extracted 6. Extracted Triadan Triadan 208, 208, fragment fragment of the of nasalthe nasal bone, bone, excised excised mass: mass: (a) lateral (a) lateral site, site, (b) medial (b) medial site. site.

TheThe skin skin and and subcutaneous subcutaneous tissues tissues were were sutured sutured as previously as previously described described (Figure (Figure7). 7). PartPart of the of massthe mass was was sent sent for histopathologicalfor histopathological examination. examination.

Figure 7. Postoperative view. Both incisions were closed with a simple interrupted suture. A drain was left in the wound after tooth extraction. It was removed 3 days after surgery, and no complications in healing were observed.

2.4. Postoperative Treatment After surgery, the horse received an administration of procaine penicillin (80,000 IU/kg IM) and streptomycin (8 mg/kg IM), which was continued postoperatively for 10 days. During the first week, flunixin meglumine (1.1 mg/kg) was administered intrave- nously as anti-inflammatory therapy. After maxillary tooth extraction, the fistula was lavaged with physiological saline solution, debrided, and plugged with iodoform gauze immersed in plaster of Paris to allow granulation and to prevent the persistence of an oronasal communication. Three, four, and nine days later, under sedation (detomidine 0.02 mg/kg IV and butorphanol 0.01 mg/kg IV) the plug was replaced and the fistula was lavaged and debrided. Sixteen days after initial surgery, a polyvinyl siloxane plug (PVS) was placed in the alveolus. The PVS plug was changed once a week under sedation, as Animals 2021, 11, x 6 of 12

(a) (b) Figure 6. Extracted Triadan 208, fragment of the nasal bone, excised mass: (a) lateral site, (b) medial site. Animals 2021, 11, 317 6 of 11 The skin and subcutaneous tissues were sutured as previously described (Figure 7). Part of the mass was sent for histopathological examination.

FigureFigure 7.7. Postoperative view. view. Both Both incisions incisions were were closed closed with with a simple a simple interru interruptedpted suture. suture. A drain A was left in the wound after tooth extraction. It was removed 3 days after surgery, and no compli- drain was left in the wound after tooth extraction. It was removed 3 days after surgery, and no cations in healing were observed. complications in healing were observed.

2.4.2.4. Postoperative Postoperative Treatment Treatment AfterAfter surgery, the the horse horse received received an anadministration administration of procaine of procaine penicillin penicillin (80,000 (80,000IU/kg IM) IU/kg and IM) streptomycinand streptomycin (8 mg/kg (8 mg/kg IM), which IM), whichwas continued was continued postoperatively postoperatively for 10 fordays. 10 days.During During the first the week, first week,flunixin flunixin meglum meglumineine (1.1 mg/kg) (1.1 mg/kg) was administered was administered intrave- intravenouslynously as anti-inflammatory as anti-inflammatory therapy. therapy. After maxillary After maxillary tooth extraction, tooth extraction, the fistula the was fistula lav- wasaged lavaged with physiological with physiological saline solution, saline solution, debrided, debrided, and plugged and pluggedwith iodoform withiodoform gauze im- gauzemersed immersed in plaster in plasterof Paris of to Paris allow to allowgranul granulationation and andto prevent to prevent the thepersistence persistence of ofan anoronasal oronasal communication. communication. Three, Three, four, four, and and nine nine days days later, underunder sedationsedation(detomidine (detomidine 0.020.02 mg/kgmg/kg IV and and butorphanol butorphanol 0.01 0.01 mg/kg mg/kg IV) IV) the the plug plug was was replaced replaced and and the thefistula fistula was waslavaged lavaged and anddebrided. debrided. Sixteen Sixteen daysdays after afterinitial initial surgery, surgery, a polyvinyl a polyvinyl siloxane siloxane plug plug(PVS) (PVS)was placed was placed in the in alveolus. the alveolus. The ThePVS PVS plug plug was was changed changed once once a week a week under under sedation, sedation, as as previously described. To improve the healing process, during each procedure fistula irritation with surgical gauze and a miniature tube brush was performed, and a new dental impression material plug was molded and inserted. Eight weeks later, endoscopic examination revealed that the oral opening of the fistula was filled with granulation tissue and mucosa, but the persistence of a 2 mm-diameter oronasal communication in the apical region of the alveolus was detected. The apical part of the plug was remodeled and adjusted to the alveolus. The plug was frequently loosened, necessitating its replacement and resulting in the contamination of the nasal cavity with feed. In the 12th week of treatment, the plug was modified by adding a small plastic sleeve into the PVS packing material, to which a nylon thread was attached. Free ends were fastened to a button fixed on the surface of the maxillary bone (Figure8). Additional injections of the fistula with platelet-rich plasma (PRP) were conducted in a once-weekly regimen for 3 weeks. Endoscopic examination performed in the 16th week of treatment revealed a markedly reduced tract of the fistula to a 1 mm diameter (Figure9). Two months later, an autologous cancellous bone graft was taken from tuber coxae to promote bony fusion and revascularization. First, the oronasal fistula was filled with graft and the alveolar cavity was then covered with a modified polyvinyl siloxane plug, as previously described, for 4 weeks. Seven months after the initial extraction, endoscopic examination revealed the complete closure of the fistula. Animals 2021, 11, x 7 of 12

previously described. To improve the healing process, during each procedure fistula irritation with surgical gauze and a miniature tube brush was performed, and a new dental impression material plug was molded and inserted. Eight weeks later, endoscopic examination revealed that the oral opening of the fistula was filled with granulation tissue and mucosa, but the persistence of a 2 mm-diameter oronasal communication in the apical region of the alveolus was detected. The apical part of the plug was remodeled and adjusted to the alveolus. The plug was frequently loosened, necessitating its replacement and resulting in the contamination of the nasal cavity with feed. In the 12th week of treatment, the plug was modified by adding a small plastic sleeve into the PVS packing material, to which a nylon thread was attached. Free ends were fastened to a button fixed on the surface of the maxillary bone (Figure 8). Additional injections of the fistula with platelet-rich plasma (PRP) were conducted in a once-weekly regimen for 3 weeks. Endoscopic examination performed in the 16th week of treatment revealed a markedly reduced tract of the fistula to a 1 mm diameter (Figure 9). Two months later, an autologous cancellous bone graft was taken from tuber coxae to promote bony fusion and revascularization. First, the oronasal fistula was filled Animals 2021, 11, 317 with graft and the alveolar cavity was then covered with a modified polyvinyl siloxane7 of 11 plug, as previously described, for 4 weeks. Seven months after the initial extraction, endoscopic examination revealed the complete closure of the fistula.

(a) (b)

AnimalsFigure 2021 8. , 11 Polyvinyl, x siloxane impression material material inserted inserted into into ne newlywly created created oro-nasal fistula ﬁstula fastened with thread and 8 of 12 button: (a) occlusal surface, (b) alveolar surface, (c) sealed occlusal surface, (d) button at the skin surface. button: (a) occlusal surface, (b) alveolar surface, (c) sealed occlusal surface, (d) button at the skin surface.

FigureFigure 9. 9.Transnasal Transnasal endoscopic endoscopic examination examination obtainedobtained 1616 weeksweeks afterafter thethe initial surgery. Note the nasalnasal opening opening of of the the persisted persisted oronasal oronasal fistula fistula at at the the level level of of 208 208 alveolus. alveolus. 3. Results 3. Results The results of the treatment should be considered satisfactory, despite the long-lasting The results of the treatment should be considered satisfactory, despite the long- complications associated with the presence of a connection between the nasal and oral lasting complications associated with the presence of a connection between the nasal and cavity. The fistula healed and, consequently, closed within 7 months after the surgical oral cavity. The fistula healed and, consequently, closed within 7 months after the surgical procedure. Histopathology revealed the benign proliferation of fibrous connective tissue procedure. Histopathology revealed the benign proliferation of fibrous connective tissue superficially (Figure 10a), with the presence of irregularly shaped trabeculae of woven bone superficially (Figure 10a), with the presence of irregularly shaped trabeculae of woven rimmed with osteoblasts separated by fibrous stroma embedded in the fibrous tissue. In bone rimmed with osteoblasts separated by fibrous stroma embedded in the fibrous the fibrous area, proliferating fibroblast-like spindle cells, collagen fibers, and blood vessels tissue. In the fibrous area, proliferating fibroblast-like spindle cells, collagen fibers, and blood vessels were present. Only a few mitotic figures were observed (Figure 10b). The histopathologic findings were consistent with ossifying fibroma.

(a) (b) Figure 10. Histological section of the mass. Benign proliferation of fibrous connective tissue superficially (a); curvilinear trabeculae of woven bone set in a fibrous stroma in deeper parts of the mass (b).

To date—i.e., 2 years after surgery—no recurrence was observed, and the horse does not show any disturbing symptoms.

4. Discussion The exact etiology of ossifying fibroma is unknown. Most OFs are found in young animals and have been reported to be present already at birth [29]. In humans, OFs are presumed to originate from mesenchymal blast cells in the periodontal ligament, not as a neoplasm but as areas of excessive bone resorption with attempted repair [30]. Some authors believe that such tumors are not neoplastic but developmental in origin, while others consider them as the ossification of changes associated with dysplasia of fibrous tissue [31]. These theories on the origin of OF remain inconclusive. In the case presented here, there was a concurrent problem with a hypoplastic and displaced tooth that had a connection with the mass. The mobility and root reabsorption of the teeth involved have frequently been described in the literature [32]. We suspect that the tumor originated from Animals 2021, 11, x 8 of 12

Figure 9. Transnasal endoscopic examination obtained 16 weeks after the initial surgery. Note the nasal opening of the persisted oronasal fistula at the level of 208 alveolus.

3. Results The results of the treatment should be considered satisfactory, despite the long- lasting complications associated with the presence of a connection between the nasal and oral cavity. The fistula healed and, consequently, closed within 7 months after the surgical Animals 2021, 11, 317 8 of 11 procedure. Histopathology revealed the benign proliferation of fibrous connective tissue superficially (Figure 10a), with the presence of irregularly shaped trabeculae of woven bone rimmed with osteoblasts separated by fibrous stroma embedded in the fibrous tissue. In the fibrouswere present. area, proliferating Only a few fibr mitoticoblast-like figures spindle were observed cells, collagen (Figure fibers,10b). Theand histopathologic blood vessels werefindings present. were Only consistent a few withmito ossifyingtic figures fibroma. were observed (Figure 10b). The histopathologic findings were consistent with ossifying fibroma.

(a) (b)

Figure 10. HistologicalFigure 10. Histological section of thesection mass. of Benignthe mass. proliferation Benign proliferation of fibrous of connective fibrous connective tissue superficially tissue (a); curvilinear superficially (a); curvilinear trabeculae of woven bone set in a fibrous stroma in deeper parts of the trabeculae of woven bone set in a fibrous stroma in deeper parts of the mass (b). mass (b). To date—i.e., 2 years after surgery—no recurrence was observed, and the horse does To date—i.e.,not 2 show years any after disturbing surgery—no symptoms. recurrence was observed, and the horse does not show any disturbing symptoms. 4. Discussion 4. Discussion The exact etiology of ossifying fibroma is unknown. Most OFs are found in young The exact etiologyanimals andof ossifying have been fibroma reported is unknown. to be present Most already OFs are at found birth [ 29in ].young In humans, OFs are animals and havepresumed been reported to originate to be frompresent mesenchymal already at birth blast cells[29]. inIn thehumans, periodontal OFs are ligament, not as presumed to originatea neoplasm from butmesenchymal as areas of blast excessive cells in bone the resorptionperiodontal with ligament, attempted not as repair a [30]. Some neoplasm but asauthors areas believeof excessive that suchbone tumors resorption arenot with neoplastic attempted but repair developmental [30]. Some in origin, while authors believeothers that such consider tumors them are asnot the ne ossificationoplastic but of developmental changes associated in origin, with while dysplasia of fibrous others considertissue them [as31 ].the These ossification theories of on changes the origin associat of OFed remain with dysplasia inconclusive. of fibrous In the case presented tissue [31]. Thesehere, theories there on was the a concurrentorigin of OF problem remain withinconclusive. a hypoplastic In the and case displaced presented tooth that had a here, there wasconnection a concurrent with problem the mass. with The a hypoplastic mobility and and root displaced reabsorption tooth ofthat the had teeth a involved have connection withfrequently the mass. beenThe mobility described and in theroot literature reabsorption [32]. Weof the suspect teeth that involved the tumor have originated from frequently beenthe described periodontal in the ligament literature of [3 Triadan2]. We suspect 208, was that the the result tumor of excessive originated tooth from repair, or that the tooth problems appeared after expansile mass growth. The most frequent location of OF is mandibular, involving the premolar and molar region [33]. OF in animals has no clear sex predilection, but in humans it has typically been more prevalent in females than males [34]. It is manifested by slow-growing progressive and painless mass formation [35]. The neighboring tissues can be pushed without being destroyed [36]. Signs of early mass growth are unspecific, causing delay in diagnosis. The case presented here was clinically asymptomatic until the tumor occupied the whole nasal cavity, causing severe breathing difficulties. A presumptive diagnosis was based on clinical examination, endoscopy, radiography, and computed tomography evaluation. In differential diagnosis, a cyst; inflammatory lesion; benign tumor, such as osteoma; fibrous dysplasia; and a tumor with a predilection for paranasal sinuses, including squamous cell carcinoma, undifferentiated carcinoma, adenocarcinoma, and osteosarcoma, were taken into consideration [22,37,38]. On radiographs, the extent of the mass could be assessed, but the exact location and the involvement of the different compartments of the nasal cavity could not be verified. Computed tomography (CT) overcame the limits of radiography, allowing for the good visualization of the size, localization, and impact on surrounded structures; it also provided the veterinary surgeon clear indications for the planned surgery [39,40]. However, the exact differentiation of the soft tissue structures was not possible. The deformation and compression of the left dorsal and ventral nasal concha were visible on the images, but full assessment could be achieved only during surgery. The CT appearance of ossifying fibromas may vary widely depending on the degree of ossification [39]. It has been observed that the edges of the lesion are usually well defined. The internal structure Animals 2021, 11, 317 9 of 11

shows a mixed radiodensity, with a pattern that depends on the form and quantity of the calcified material [41]. The only disadvantage of a CT scan is the need for general anesthesia, which entails considerable risk of complications during both the anesthetic period and recovery [42]. A definitive diagnosis was based on histopathology [43]. The differentiation of certain benign neoplasms such as osteoma and fibrous dysplasia may be difficult [44]. It has been suggested that ossifying fibroma has the features of both osteoma and fibrous dysplasia [18]. One report described a case of osteoma with features of an ossifying fibroma [45]. There is also a suggestion that an OF may mature into an osteoma [29]. The horse’s temperament and behavior allowed the surgery to be conducted as a standing procedure; therefore, the cost of the procedure and the risk of postoperative complications of standing up due to hemorrhage were significantly reduced. Surgery started with the dental extraction of Triadan 208. In this case, a dorsal approach to the roots through the external maxillary bone trephination and repulsion was recommended and more appropriate than the lateral approach through the buccal soft tissues (buccotomy) because of the oblique position and displacement into the nasal cavity [46]. The persistence of oro–nasal fistula was a problematic complication. Probably in the initial period of treatment, the polyvinyl siloxane plug was incorporated too high, which prevented the alveolar closure of the upper part by granulation tissue. A later problem was keeping the packing material firmly in the alveolus. It was necessary to modify this method by adding a small plastic sleeve into the PVS packing material, which was attached by nylon thread to the button fixed on the surface of the maxillary bone. This method allowed the alveolar material to be maintained for a long time. The only observed side effect was that skin inflammation occurred due to the sutured button. To release the mass completely, it was necessary to make an additional excision of a nasal bone osteotomy. A direct approach to the nasal cavity via osteotomy over the nasal bone was described and is recommended for conditions such as an ethmoid hematoma, paranasal sinus cyst, and neoplasia, or in cases in which the preoperative diagnosis is uncertain [47–49]. This approach allows the tumor to be easily and quickly released from the surrounding tissues. The wound was traditionally closed with a simple interrupted suture, which provided good conditions for wound revision if necessary. OFs tend to recur if they are not completely excised, and follow-up radiography is advised to monitor any re-growth [2,38]. As an alternative, radiation and chemotherapy have been used effectively to treat the recurrence of these tumors after surgery or as sole treatment [38,50]. Furthermore, complete surgical excision is associated with a higher number of successful reported cases [2,4,14,30].

5. Conclusions In conclusion, signs of early mass growth are unspecific and cause a delay in diagnosis. A preliminary diagnosis of ossifying fibroma can be made from its clinical appearance, its site of development, the age of onset, radiography, and CT, with subsequent definitive diagnosis after histopathology. Total removal is considered ideal for OF and is reported to reduce recurrence and improve the outcome. In this paper, computed tomography played an important role in the diagnostic procedure. Surgery was successful because the mass was well circumstanced. A direct approach to the nasal cavity through a bone appeared to be a good technique for tumor removal from the nasal cavity. In the presented case, the extraction and removal of the tumor was achieved, though the oronasal fistula represented the most challenging problem. A satisfying outcome was achieved using a modified PVS plug, but a significant improvement in complete closure was noticeable after the application of an autologous bone graft.

Author Contributions: Conceptualization, B.T.; methodology, B.T.; performing surgery, B.T. and K.G.; anesthesia, O.D. and R.B.; writing—original draft preparation, B.T.; writing—review and editing, O.D., K.G., N.K. and R.S. All authors have read and agreed to the published version of the manuscript. Animals 2021, 11, 317 10 of 11

Funding: This research received no external funding. Institutional Review Board Statement: Ethical review and approval were waived for this study, due to the observational character of the study and the fact that the animals included in the study were patients of the clinic, and described methods were part of the therapy. Data Availability Statement: Not applicable. Conﬂicts of Interest: The authors declare no conﬂict of interest.

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