116 Test 98.2 ORAL MEDICINE

Developmental Mandibular Salivary Gland Defect The Importance of Clinical Evaluation

developmental mandibular salivary gland defect (also known as static A , static bone defect, Stafne bone cavity, latent bone cyst, latent bone defect, idiopathic bone cavity, developmen- tal submandibular gland defect of the , aberrant salivary gland defect in the mandible, and lingual mandibular bone Sako Ohanesian, concavity) is a deep, well-defined depression DDS in the lingual surface of the posterior body of the mandible. More precisely, the most common location is within the submandibu- lar gland fossa and often close to the inferi- or border of the mandible. In developmental bone defects investigated surgically, an aberrant lobe of the submandibular gland extends into the bony depression. First recognized by Dr. Edward Stafne in 1942, numerous cases of developmental mandibular salivary gland defect have since been reported, and the lesion should not be considered rare.1 In a study of 4963 pan-

Most authorities now agree that this entity is a congenital defect, although it has rarely been observed in children and its precise anatomic nature is still uncertain.

oramic images of adult patients, 18 cases of Figure 1. CT slices/panoramic views showing a well-defined radiolucent lesion in the right mandible. salivary gland depression were found by Karmiol and Walsh2, an incidence of nearly 0.4%. Most authorities now agree that this The margins of the radiolucent defect are around an extension of salivary tissue. This entity is a congenital defect, although it has well-defined by a dense radiopaque line. theory is supported by findings of radiolu- rarely been observed in children and its pre- This cortical margin is usually thicker on cencies in association with each of the 3 sali- cise anatomic nature is still uncertain. Also the superior aspect. This appearance is the vary glands. Most surgical series have noted unexplained is the fact that far more cases result of the x-rays passing tangentially salivary tissue within the bony defect, but have been reported in men than in women.3 through the relatively thick walls of the muscle, lymphatic tissue, and blood vessel The lesion, usually asymptomatic and depression. It is occasionally bilateral. The have also been reported. discovered during routine radiographic ex- radiolucent defect may represent either The lesion may be regarded properly as amination, appears as an ovoid radiolucen- actual enclavement of salivary gland tissue a developmental defect rather than a patho- cy, generally situated between the mandibu- within the mandible during embryonic logic lesion. Histologically, normal salivary lar canal and the inferior border of the development or, more frequently, an inden- tissue is found, and no treatment is required mandible, just anterior to the angle. Rare tation on the mandible with a portion of the except routine radiographic follow-up. It can examples are located in the apical region of submaxillary gland lying within the defect. and should be differentiated from the trau- the mandibular premolars or cuspids, and Salivary gland defects are presumed to form matic bone cyst (also referred to as hemor- are related to the sublingual gland fossa. by the remodeling of the mandibular cortex continued on page 118

DENTISTRY TODAY ¥ FEBRUARY 2008 118 ORAL MEDICINE Developmental Mandibular... continued from page 116

Xxxx...Table. Comparison of Various Lesions That Can Be Confused With Static Bone Defect. 7,12,13

Etiology Clinical Presentation Radiographic Findings Diagnosis Treatment Prognosis

Traumatic Unknown in most cases; may Peaks in second decade; usual- Clearly defined radiolucency; Radiographic appearance; clini- Surgical exploration; observa- Excellent; small risk of recur- bone cyst be due to traumatic injury pro- ly in body of mandible; pain- margins may be uneven but cal finding of an empty bony tion for resolution. rence. ducing intramedullary hemor- less in most cases; swelling clear; may extend between space (pseudocyst); collagen rhage and subsequent clot noted in one fourth roots creating and fibrin line the dead space; resorption; alternative theory of cases. a scalloped pattern. lamellar bone may be noted suggests degeneration of pri- along the bony margin. mary intrabony pathology.

Mandibular salivary Developmental depression of No symptoms; discovered Round to ovoid radiolucency Radiographic appearance. Recognition only. Excellent. gland defect (Stafne the lingual side of the incidentally. below inferior alveolar canal, bone cavity) mandible; the aberrant lobe of above inferior border and the submandibular salivary below third molar area; well- gland and/or adipose tissue defined by a dense hypercorti- fills the body of mandible cated margin; size range of one defect; depression created pro- to 3 cm; rarely noted in premo- duces characteristic radi- lar and canine areas. ographic findings.

Periapical A radicular cyst that most likely Often, periapical cysts do not Located approximately in the A cyst that becomes large may Treatment of a tooth with a Excellent; recurrence is cyst results when rests of epithelial produce symptoms unless sec- apex of a nonvital tooth; occa- cause swelling; the swelling radicular cyst may include unlikely if removed completely. cells in the periodontal liga- ondary infection occurs. sionally, appear on the mesial may feel bony and hard if the extraction, endodontic therapy, ment are stimulated by inflam- or distal surface of a tooth cortex is intact, crepitant as the and apical ; treatment matory products from a nonvi- root, at the opening of an bone thins, and rubbery if of a large cyst usually involves tal tooth. accessory canal, or infrequent- bone destruction has occurred; surgical removal or marsupial- ly in a deep periodontal pocket; outline of cyst is usually ization. most (60%) found in the curved or circular unless maxilla. influenced by surrounding structures such as cortical boundaries.

Dentigerous A developmental odontogenic Most commonly involves fre- Well-defined radiolucency Cysts without secondary Cyst enucleation and extraction Excellent; possible complica- cyst cyst arising subsequent to sep- quently impacted teeth: enclosing crown of unerupted inflammation are thin, cuboidal, of associated tooth; marsupial- tions include: pathologic frac- aration between dental follicle mandibular third molars, fol- tooth; corticated/opaque mar- nonkeratinized epithelial lining ization prior to excision may be ture with large lesions and and the crown of an associated lowed by maxillary canines; gins unless infected; may pro- 2 cell layers thick with flat considered if very large. neoplastic transformation of unerupted tooth; proliferation usually noted during second duce root resorption of adja- epithelial-connective tissue epithelial lining. of reduced enamel epithelium and third decades; asympto- cent erupted teeth; usually interface; loosely arranged col- lining the follicle, with fluid matic and discovered on rou- unilocular; less commonly lagen bundles; cysts with sec- accumulation between epitheli- tine radiographic examination; multilocular. ondary inflammation have um and impacted tooth crown; painless /alveolar expansion hyperplastic, nonkeratinized degeneration of the stellate may occur; cortex is thinned squamous epithelial lining with reticulum component of enam- and rarely perforated. epithelial ridge development; el organ occurs during odonto- variable chronic inflammatory genesis. cell infiltrate within condensed collagen stroma.

Odontogenic A benign, aggressive develop- 5% to 15% of odontogenic Can occur in any area of maxil- Radiographic features. Excision with curettage of bony Recurrence rate varies from keratocyst mental ; may cysts; usually occurs sporadi- la or mandible; rarely may confines. 10% to 30% (greatest in be associated with mutation of cally as an isolated finding; arise in gingival soft tissue patients with a syndrome). PTCH tumor suppressor gene. about 5% are associated with only, mandible is preferred site nevoid basal cell carcinoma; in 65% to 78% of cases; often 5% of patients have multiple seen in a dentigerous relation- odontogenic keratocysts ship; discrete radiolucency, (OKCs) and no syndrome. usually in relation to teeth; may be unilocular to multilocular.

Nonossifying Unknown in most cases; Majority of all NOFs are On plain film radiographs, Histologically, the lesions con- Treatment varies depending on Generally excellent. lesions occur as a result of asymptomatic and are discov- NOFs appear as eccentric, tain whorled bundles of con- the size and severity of the developmental aberrations at ered incidentally on radi- multi or uniloculated, ovoid nective tissue cells admixed NOF; surgery is often not the epiphyseal plate; not neo- ographs; symptomatic lesions lesions in the metaphysis of with foamy histocytes, hemo- required to treat NOF due to a plasms, but developmental may present with mild pain bone with sclerotic margins; siderin, hemorrhage, collagen, high rate of spontaneous defects; tend to occur after the and swelling of short duration; lesions may extend into the multinucleated giant cells, and regression and a lack of symp- age of 2, a muscle pull and may have bone tenderness medullary cavity; long axis of bone trabeculae. toms; symptomatic lesions periosteal injury may be a con- with palpation. the NOF is most commonly should first be treated conserv- tributing factor. seen parallel to the long axis of atively—conservative care con- the bone and are usually locat- sists of limited activity and ed medially. immobilization, in addition to yearly or bi-yearly radiographs; curettage or bone grafting.

DENTISTRY TODAY ¥ FEBRUARY 2008 119

Etiology Clinical Presentation Radiographic Findings Diagnosis Treatment Prognosis

Fibrous Unknown in most cases; Occurs with equal predilec- Generally a small unilocular radi- Monostatic fibrous dysplasia is often Surgical removal of lesion. Majority of lesions are too dysplasia skeletal aberrations consti- tion for males and females; olucency or a somewhat larger discovered as an incidental radi- large at the time of original tute the cardinal feature; the more common in children multilocular radiolucency; both ographic finding; patients with jaw diagnosis to excise surgical- condition is often monostot- and young adults; painless with a rather well-circumscribed involvement first may complain of ly without leaving facial ic, but may be polyostotic; swelling or bulging of the border and containing a network unilateral facial swelling or an enlarg- deformity or, in the case of monostatic fibrous dysplasia jaw; swelling usually of fine bony trabeculae; increased ing deformity of the alveolar process; the mandible, weakening of is of greater concern to the involves the labial or buccal trabeculation could render the pain and pathologic fractures are the bone so as to invite dentist due to frequency plate, seldom the lingual lesion more opaque; the periph- rare; if extensive craniofacial lesions pathologic fracture; numer- with which are affected; aspect; possible malalign- ery of lesions most commonly is have impinged on nerve foramina, ous cases reported in which nearly every bone has been ment, tipping or displace- ill defined, with a gradual blend- neurologic symptoms such as anos- monostotic fibrous dyspla- reported involved. ment of teeth; mucosa is ing of normal trabecular bone mia, deafness, or blindness may sia has undergone sponta- almost invariably intact over into an abnormal trabecular pat- develop. neous malignant transfor- the lesion. tern. mation into sarcoma.

Ameloblastoma A benign, aggressive jaw Peak incidence during third Osteolytic or radiolucent with Sheets, strands, islands of odonto- Varies with subtype, size, Generally good, recurrence tumor of odontogenic to fifth decades; 80% occur sclerotic, smooth, even borders; genic epithelium; peripheral layer of and location; solid/multi- rates higher with conserva- epithelial ectodermal origin; in the mandible, chiefly in may be unilocular to multilocular; cuboidal to columnar ameloblast- cystic lesions generally tive treatment; recurrence the most common odonto- molar and ramus region; root resorption or tooth displace- like cells enclosing a cell population require local incision or rates of up to 15% follow- genic tumor after the odon- often presents in association ment may be seen; can expand analogous to stellate reticulum of resection; cystic variant ing marginal resection; toma; incidence of 0.3 cases with unerupted third molar affected jaw; cortical perforation the enamel organ; several histologic requires local excision as long-term follow-up per million people. teeth; may produce marked may occur. patterns described have no clinical recurrences may follow necessary. deformity, facial asymmetry; relevance; malignant variants rarely curettage only. peripheral variant arises in seen. gingival tissue of older adults fifth to seventh decades; slow growing, but persistent.

Giant Probably reactive or respon- Bony expansion; most cases Usually multilocular, occasionally Incisional biopsy; primary hyper- Thorough curettage; margin- Aggressive variant has high cell tumor sive in nature; speculation in those less than 30 years unilocular, radiolucency; margins parathyroidism should be ruled out. al resection if aggressive or recurrence rate; generally suggests it may present a of age; female predomi- are usually well defined; borders recurrent; Calcitonin may be good. developmental anomaly . nance; near exclusivity in may be scalloped; can displace successful in some cases; mandible or maxilla—rarely teeth; wide-size variation at time intralesional corticosteroid in facial bones; occurrence in of presentation. placement in small lesions mandible predominates 3:1 may be successful. over that in maxilla; usually anterior to molar teeth; most cases are nonaggressive, slow growing, and asympto- matic; some cases are recur- rent and exhibit aggressive behavior with pain, perfora- tion, and rapid enlargement; no radiographic or histologic features can be used to sep- arate nonaggressive lesions from aggressive lesions.

Focal Etiology is unknown but has In reported cases, 77% Lesion has a predilection for the The roentgenographic appearance of Recognition only; when Good. osteoporotic been postulated to be bone occurred in women, and mandibular molar area, generally the focal osteoporotic bone marrow doubt exists about the true bone marrow marrow hyperplasia, per- they involved the mandible appears as a radiolucency of vari- defect of the jaws is not unlike that nature of the radiolucency, a defect sistent embryologic marrow in 83% of cases; asympto- able size, a few millimeters to a of residual dental infections, central longitudinal study with films remnants, or site of abnor- matic and discovered only centimeter or more, with a poorly neoplasms, or even the traumatic at 3-month intervals may be mal healing following during routine roentgeno- defined periphery indicative of cyst of bone. prescribed; the marrow extraction, trauma, or graphic examination. lack of reactivity of adjacent space should not increase local inflammation. bone; most common in edentu- in size. lous areas, suggesting they result from failure of normal bone regeneration after tooth extrac- tion.

Basal A hereditary condition, Complex syndrome which Multiple keratocysts may devel- Starts to appear early in life, usually High recurrence rate of the It is reasonable to examine cell nevus transmitted as an autosomal includes a variety of possible op bilaterally and can vary in after 5 years of age and before 30, keratocysts associated with the patient yearly for new syndrome dominant trait, with high abnormalities including den- size from one mm to several with development of jaw cysts and this syndrome; several cases and recurrent cysts; a penetrance and variable tal and osseous anomalies centimeters in diameter; a skin, basal cell carcinomas; lesions of ameloblastoma have panoramic film serves as an expressivity. such as odontogenic kerato- radiopaque line of the calcified occur in multiple quadrants; the pres- developed in cysts, thus adequate screening film; cysts and mild mandibular falx cerebri may be prominent ence of cortical boundary and other emphasizing the importance referral for genetic counsel- . on the posteroanterior skull pro- cystic characteristics differentiate of surgical removal of the ing may be appropriate. jection; occasionally the calcifi- basal cell nevus syndrome from other cysts and their histologic cation may appear laminated. abnormalities characterized by multi- examination. ple radiolucencies.

Brown May appear in any bone, but Variably defined margins Occasionally peripical radi- Manifestations cover a broad range, Surgical removal; the site of After successful surgical tumor in are frequently found in the and may produce cortical ographs reveal loss of the lamina but most patients have renal calculi, brown tumor heals with removal of the causative hyperparathy- facial bones and jaws; these expansion; if solitary, tumor dura in patients with hyper- peptic ulcers, psychiatric problems, bone that is radiographically parathyroid adenoma, roidism lesions may be multiple may resemble a central giant parathyroidism; loss of lamina or bone and joint pain; gradual loos- more sclerotic than normal. almost all radiographic within a single bone. cell granuloma, therefore, if dura may occur around one tooth ening, drifting, and loss of teeth may changes revert to normal; a giant cell granuloma or all the remaining teeth. occur; because of daily fluctuations, the site of a brown tumor occurs later than the second the serum calcium level should be often heals with bone that is decade, the patient should tested at different intervals; the radiographically more scle- be screened for an increase serum alkaline phosphatase level may rotic than normal. in serum calcium, PTH, and be elevated in hyperparathyroidism. alkaline phosphatase.

continued on page 120

FEBRUARY 2008 ¥ DENTISTRY TODAY 120 ORAL MEDICINE

Developmental Mandibular... the roentgenogram as a rather continued from page 119 poorly circumscribed radiolucency in a location between the central rhagic bone cyst). The traumatic incisor and first premolar area. bone cyst is an uncommon, unlined They are far less common than the cavity of the jaws. Clinically, the posterior lesion. A complication lesion is asymptomatic in the major- occasionally reported in the litera- ity of cases and is often accidentally ture is the development of a true discovered on routine radiological central salivary gland neoplasm examination. Pain is the presenting from the included salivary gland symptom in 10% to 30% of the tissue, but this is rare.7 patients. Other, more unusual sym- ptoms include tooth sensitivity, CASE REPORT paresthesia, fistulas, delayed erup- The patient in this case was a white tion of permanent teeth, displace- 36-year-old male, with failed en- ment of the inferior dental canal, dodontic therapy involving tooth and pathologic fracture of the man- No. 19. The patient was healthy Figure 2. Lesion in standard panoramic x-ray and implant placement. dible.4-6 Expansion of the cortical (ASA I), did not report any relevant plate of the jawbone is often noted, information regarding medical or usually buccally, resulting in intrao- dental history, and did not mention bone cavity was made, and no fur- Dental professionals are facing ral and extraoral swelling and sel- the use of any medication. Ex- ther therapy was instituted. The an ever-increasing emphasis on a dom causing deformity of the face. pansion of the mandible and hydra- pathologist’s recommendation was thorough clinical examination of On radiological examination, a tion of mucous membrane were nor- to simply observe the area radi- each patient. As a result, the dentist traumatic bone cyst usually ap- mal. Endodontic consultation con- ographically in the event that it is often confronted with the need to pears as a unilocular radiolucent firmed root fracture, and the tooth became enlarged and would necessi- further evaluate any deviation from area with an irregular but well- was extracted and replaced with a tate a surgical biopsy. normal, including the decision to defined (or partly well-defined) out- root form implant. The option of a 3- biopsy a suspected lesion. To avoid line, with or without sclerotic lin- unit bridge was given to patient. DISCUSSION any unnecessary procedures and ing around the periphery of the The radiograph disclosed a well cir- Many terms have been used to treatments, it is important to be lesion. The traumatic bone cyst cumscribed radiolucency inferior describe asymptomatic radiolucen- aware of the existence of other almost invariably lies above the to the mandibular canal and located cies at the angle of the mandible. anatomic variations in the exami- mandibular canal on the intraoral in the region of the right mandib- Similar defects related to the sub- nation process. Awareness of these periapical roentgenogram, while the ular second and third molars lingual and parotid glands have entities can save the patient from salivary gland depression lies below (Figures 1 and 2). The diameter been described, located at the unnecessary invasive procedures. the canal. Nevertheless, definitive measured approximately 2 cm. No mandibular symphysis and the Most case reports of Stafne bone differential diagnosis from other symptoms were reported. mandibular rami, respectively.8-10 cavities have discussed the find- lesions sometimes cannot be made On 3-dimensional imaging views Some researchers apply the term ings on intraoral dental films, plain without surgical exploration. of the lingual aspect of the man- Stafne bone cyst to lesions associat- films of the mandible, or orthopan- It has been recognized that a dible obtained with a NewTom 3D ed with any of the salivary glands, tographs. Although these imaging sublingual salivary gland depression cone beam CT scanner (AFP Im- while others restrict the term to the techniques are often sufficient for or inclusion may occur on the lingual aging Corp), it was observed that submandibular gland, preferring diagnosis, they may not be definitive surface of the anterior segment of this radiolucency represented a cor- more specific terms such as anterior when the lesion is atypical. In these the mandible. These asymptomatic tical indentation or depression lingual mandibular salivary gland situations, confirmatory testing is lesions have generally appeared on (Figure 3). A diagnosis of for the sublingual gland.11 warranted, as the differential diag- nosis for mandibular radi- olucencies includes traumat- ic bone cyst, , , , nonossifying fi- broma, fibrous dysplasia, am- eloblastoma, giant cell tu- mor, focal osteoporotic bone marrow defect, basal cell nevus syndrome, and brown tumor of hyperparathyroid- ism. (See Table.7,12,13)

CONCLUSION Given the possible clinical presentation of the various lesions described, it is im- portant for the dentist to be aware of the existence of these anatomic variations in the examination process. Cystic-appearing lesions that occur in the mandible are often difficult to distin- guish from one another with radiography. They are all usually benign, but some can be locally aggressive and destructive. The patient FREEinfo, circle 86 on card 121

Continuing Education Test No. 98.2 o submit Continuing Education answers, use the answer sheet on page 122. On the answer sheet, identify the article (this one is Test T 98.2), place an X in the box corresponding to the answer you believe is correct, detach the answer sheet from the magazine, and mail to Dentistry Today Department of Continuing Education.

The following 8 questions were derived from the article Developmental Mandibular Salivary Gland Defect: The Importance of Clinical Evaluation by Sako Ohanesian, DDS, on pages 116 through 121.

Learning Objectives After reading this article, the individual will learn: ¥ to differentiate a developmental salivary gland defect from traumatic bone cysts and other lesions. ¥ to recognize the clinical and radiographic appearance of a develop- mental mandibular salivary gland defect (the intention is to avoid unnecessary biopsy).

1. A developmental salivary gland 5. The developmental salivary defect is located: gland defect is best described a. above the mandibular canal. as: b. below the mandibular canal. a. benign neoplasm. c. at the crest of the bone. b. variations of normal. d. at the tuberosity. c. cyst. d. a premalignant lesion.

2. Treatment for a salivary gland Figure 3. The 3-D images show a cortical depression. defect includes: 6. Differential diagnosis for man- a. chemotherapy. dibular radiolucencies may b. surgical intervention. include: history and careful consideration of resembling developmental bone cavity a. dentigerous cyst. (Stafne). Proc Finn Dent Soc. 1985;81:215- c. radiation. the location of the lesion within the 221. d. none—recognition only. b. traumatic bone cyst. mandible, its borders, its internal 10. Barker GR. A radiolucency of the ascending c. odontogenic keratocyst. ramus of the mandible associated with invest- architecture, and its effects on ed parotid salivary gland material and analo- d. all of the above. adjacent structures generally make gous with a Stafne bone cavity. Br J Oral 3. Clinical presentation of the sali- it possible to narrow the differen- Maxillofac Surg. 1988;26:81-84. 11. Barak S, Katz J, Mintz S. Anterior lingual vary gland defect is: tial diagnosis. Awareness of these 7. Size of the Stafne bone defect mandibular salivary gland defect: a dilemma in a. asymptomatic—discovered inci- entities can save the patient from diagnosis. Br J Oral Maxillofac Surg. 1993; usually ranges between: 31:318-320. dentally. unnecessary treatment and unwar- a. 3 to 5 mm. 12. Scuibba JJ, Regezi JA, Rogers RS III. PDQ b. painless swelling. ranted procedures. ! Oral Disease: Diagnosis and Treatment. b. 1 to 3 mm. Lewiston, NY: BC Decker; 2002. c. bulging of the jaw. c. 3 to 5 cm. 13. White SC, Pharoah MJ. Oral Radiology: d. painful swelling. References Principles and Interpretation. 5th ed. St Louis, d. 1 to 3 cm. MO: Mosby; 2003. 1. Stafne EC. Bone cavities situated near the angle of the mandible. J Am Dent Assoc. 1942;29:1969-1972. 4. Incidence rate of Stafne bone 8. 2. Karmiol M, Walsh RF. Dental caries after Acknowledgment Which of the following tech- defect is nearly: radiotherapy of the oral regions. J Am Dent Special thanks to Dr. Brian Cooper, niques are useful in diagnosing Assoc. 1975;91:838-845. a. 0.4%. oral surgeon for diagnosing the case, the Stafne bone cyst? 3. Buchner A, Carpenter WM, Merrell PW, et al. b. 4%. Anterior lingual mandibular salivary gland and Dan D’Amoure, RT, for provid- a. periapical x-ray defect. Evaluation of twenty-four cases. Oral c. 40%. ing the CT scans. b. panoramic x-ray Surg Oral Med Oral Pathol. 1991;71:131-136. d. 0.1%. 4. Howe GL. “Haemorrhagic cysts” of the c. cone beam CT imaging mandible. I. Br J Oral Surg. Jul 1965;3:55-76. d. all of the above 5. Howe GL. “Haemorrhagic cysts” of the mandible. II. Br J Oral Surg. Nov 1965;3: 77-91. 6. Huebner G, Turlington EG. So-called traumat- Dr. Ohanesian is in private practice in ic (hemorrhagic) bone . Anaheim, California. He is a Fellow of the Review of the literature and report of two Academy of General Dentistry and the unusual cases. Oral Surg Oral Med Oral International Congress of Oral Implantolo- Pathol. 1971;31:354-365. gists, and is an Associate Fellow of the 7. Shafer WG, Hine MK, Levy BM. A Textbook of American Academy of Implant Dentistry. He Oral Pathology. 3rd ed. Philadelphia, PA: WB can be reached at [email protected]. Saunders; 1974:33. 8. Richard EL, Ziskind J. Aberrant salivary gland Continuing our tissue in mandible. Oral Surg Oral Med Oral Disclosure: Dr. Ohanesian is not affiliated “Journey of Excellence” Pathol. 1957;10:1086-1090. with NewTom Dental and has no financial 9. Wolf J. Bone defects in mandibular ramus interest in the company.

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