Sertoli Cell Tumor (SCT) in a Captive Black Bear (Ursus Americanus)

veterinary sciences

Case Report Sertoli Cell Tumor (SCT) in a Captive Black Bear (Ursus americanus)

Ahmed K. Elfadl 1,2, SunYoung Park 1,2, H M Arif Ullah 1,2, Soong-Hee Youn 3, Myung-Jin Chung 1,2, Ji-Yoon Son 1,2, Jae-Yeong Lee 1,2, Seoung-Woo Lee 1, A-Rang Lee 1, Su-Min Baek 1, Sul-Gi Jeon 1, Eun-Joo Lee 1, Il-Hwa Hong 4 , Jin-Kyu Park 1,2,* and Kyu-Shik Jeong 1,2,*

1 Department of Pathology, College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Korea; [email protected] (A.K.E.); [email protected] (S.P.); [email protected] (H.M.A.U.); [email protected] (M.-J.C.); [email protected] (J.-Y.S.); [email protected] (J.-Y.L.); [email protected] (S.-W.L.); [email protected] (A.-R.L.); [email protected] (S.-M.B.); [email protected] (S.-G.J.); miﬀ[email protected] (E.-J.L.) 2 Stem Cell Therapeutic Research Institute, Kyungpook National University, Daegu 41566, Korea 3 Samsung Everland Zoological Garden, Yongin-si, Gyeonggido 17203, Korea; [email protected] 4 Department of Veterinary Pathology, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea; [email protected] * Correspondence: [email protected] (J.-K.P.); [email protected] (K.-S.J.)

Received: 6 August 2019; Accepted: 25 September 2019; Published: 26 September 2019

Abstract: A black bear of 29-year-old (Ursus americanus) died unexpectedly in captivity without any gross lesions or clinical signs. We identified a firm, lobulated, yellowish tan, and well-circumscribed mass embedded inside the testicular tissue at the time of necropsy. The tumor sections exhibited soft necrotic and hemorrhagic areas beneath its capsule. Histologically, the tumor comprised Sertoli cells arranged in tubules and solid sheets supported by prominent fibrous connective tissues. The Sertoli cells were positive for vimentin and ER-β expression, whereas it showed negative staining for inhibin-α, cytokeratin 19, and S-100. To the best of our knowledge, this is the rare case report of testicular Sertoli cell tumor in black bear.

Keywords: Sertoli cells; testes; Ursidae; neoplasm; vimentin

1. Introduction Based on literature reports, testicular tumors are most commonly observed in dogs. Seminomas are the most prevalent testicular neoplasms in elderly horses, whereas teratoma is more frequently diagnosed in young horses. Cats, boar, rams, and bucks are rarely aﬀected by testicular tumors. However, both seminoma and Sertoli cell tumors have been observed in these species [1]. In the family Ursidae, the reported cases of neoplasms include extrahepatic biliary carcinoma in sloth bears, thyroid gland tumors, or squamous cell carcinomas of the larynx in a North American black bear, mandibular osteoma, papillary cyst adenocarcinoma of the mammary gland, or mucinous cholangiocarcinoma in a Himalayan brown bear [1–6].

2. Case Presentation A testicle tissue sample from a black bear (Ursus americanus) at the Everland Zoo in Seoul, South Korea was sent to the veterinary pathology laboratory at Kyungpook National University for pathological examination. The bear was emaciated and died without any other abnormality at 29 years of age.

Vet. Sci. 2019, 6, 77; doi:10.3390/vetsci6040077 www.mdpi.com/journal/vetsci Vet. Sci. 2019, 6, 77 2 of 5

Vet. Sci. 2019, 6, 77 2 of 5 Gross description of the lesion was followed by routine processing, hematoxylin and eosin (H&E) stainingGross of 5-descriptionµm thick sections. of the lesion Markers was including followed ER- byα routine, ER-β, inhibin-processing,α, cytokeratin hematoxylin 19, S-100,and eosin and vimentin(H&E) staining immunoglobulins of 5-μm thick were sections. used to Markers determine including the type ER- of tumor.α, ER- Grossβ, inhibin- examinationα, cytokeratin of the tumor19, S- showed100, and a vimentin ﬁrm, lobulated, immunoglobulins yellow tan, andwere well-circumscribed used to determine massthe type embedded of tumor. inside Gross testicular examination tissue (Figureof the tumor1). Section showed of the a firm, tumor lobulated, revealed yellow that the ta neoplasmn, and well-circumscribed had soft necrotic areasmass withembedded hemorrhage inside beneathtesticular the tissue capsule. (Figure 1). Section of the tumor revealed that the neoplasm had soft necrotic areas with hemorrhage beneath the capsule.

Figure 1.1. Cross section of the testicular tumor isolated from a black bear showing yellow, tan, and lobulatedlobulated neoplasm,neoplasm, whichwhich isis isolatedisolated fromfrom aa nearbynearby tissuetissue byby aa ﬁbrousfibrous capsule.capsule.

Histologically, thethe tumor tumor consisted consisted of of tubular tubular and and solid solid proliferation proliferation of of Sertoli Sertoli cells, cells, supported supported by aby ﬁbrous a fibrous connective connective tissue tissue (Figure (Figure2A). The2A). tubules The tubules varied varied in size in and size generally and generally lacked alacked lumen a exceptlumen inexcept a limited in a limited area. In area. some In areas, some multiple areas, multiple tubules mergedtubules togethermerged together to form large to form round large nests round of Sertoli nests cells,of Sertoli an interstitial cells, an interstitial space isolated space these isolated nests these from nests the surrounding from the surrounding tissues (Figure tissues2B). (Figure Individual 2B). cellsIndividual were spindle-shaped cells were spindle-shaped and tall, showing and tall, intensely show stained,ing intensely thin, spindlestained, nuclei thin, thatspindle lacked nuclei nucleoli. that Interestingly,lacked nucleoli. spindle-shaped Interestingly, Sertoli spindle-shaped cells formed Sertoli a bridge cells extending formed a from bridge one extending side of the from inner one tubules side toof thethe otherinner sidetubules (Figure to the2C). other Occasionally, side (Figure a few 2C). well-di Occasionally,ﬀerentiated a few Sertoli well-differentiated cells were observed Sertoli to havecells awere large observed round nuclei to have and a largelarge amounts round nuclei cytoplasm and large (Figure amounts2D). Hyalinized cytoplasm and (Figure dilated 2D). blood Hyalinized vessels wereand dilated observed blood in tumor vessels stroma. were observed in tumor stroma. For immunohistochemistry, tissue sections were deparaffinized, rehydrated, blocked with 3% hydrogen peroxide in methanol, and transferred into a citrate buffer (pH 6.0) and microwave treated for antigen retrieval. Washing in phosphate-buffered saline (PBS), sections were incubated with the primary antibody for 1 h at room temperature. Then, antigen-antibody complex was visualized by an avidin-biotin peroxidase complex solution (ABC kit, Vector Laboratories, Bulingame, CA, USA) and followed using diaminobenzidine (DAB). Immunohistochemical analysis revealed that the neoplasm was positive for vimentin (Figure 3A) and ER-β immunoglobulins (Figure 3B), whereas cytokeratin 19, S-100, and inhibin-α were negative. Vet. Sci. 2019, 6, 77 3 of 5 Vet. Sci. 2019, 6, 77 3 of 5

Vet. Sci. 2019, 6, 77 3 of 5

Figure 2. Histopathological picture of Sertoli cell tumor isolated from the testicle of a black bear. (A) FigureGeneral 2. overviewHistopathological of Sertoli picture cells arranging of Sertoli in cell a tubular tumor pattern isolated with from an the occluded testicle lumen. of a black H&E bear. staining. (A) GeneralBar = 200 overviewµm. (B) Severalof Sertoli tubules cells containing arranging Sertoli in a tubular cells merged pattern together with formingan occluded multiple lumen. large roundH&E staining.masses ofBar varied = 200 sizesμm. ( (indicatedB) Severalby tubules arrow). containing H&E staining. Sertoli Bar cells= merged100 µm. together (C) Spindle-shaped forming multiple Sertoli largecells showinground masses dark nucleiof varied and sizes small (indic amountsated of by cytoplasm, arrow). H&E these staining. cells formed Bar = a bridge100 μm. across (C) Spindle- the inner shapedsides of Sertoli tubules. cells H&E showing staining. dark Bar nuclei= 50 µandm. small (D) Well-di amountsfferentiated of cytoplasm, Sertoli thes cellse showingcells formed round-to-oval a bridge acrossnuclei the forming inner irregularsides of shapedtubules. tubules H&E staining. (indicated Bar by = arrow). 50 μm. H&E (D) staining.Well-differentiated Bar = 50 µ m.Sertoli cells showing round-to-oval nuclei forming irregular shaped tubules (indicated by arrow). H&E staining. ForFigure immunohistochemistry, 2. Histopathological picture tissue of Sertoli sections cell weretumor depara isolatedffi fromnized, the rehydrated,testicle of a black blocked bear. with(A) 3% Bar = 50 μm. hydrogenGeneral peroxide overview in methanol,of Sertoli cells and arranging transferred in intoa tubular a citrate pattern buff erwith (pH an 6.0) occluded and microwave lumen. H&E treated for antigenstaining. retrieval. Bar = 200 Washingμm. (B) Several in phosphate-bu tubules containingffered Sertoli saline cells (PBS), merged sections together were forming incubated multiple with the primarylarge antibody round masses for 1 hofat varied room sizes temperature. (indicated Then,by arrow). antigen-antibody H&E staining. complexBar = 100 wasμm. visualized(C) Spindle- by an avidin-biotinshaped Sertoli peroxidase cells showing complex dark solution nuclei and (ABC small kit, amounts Vector of Laboratories, cytoplasm, thes Bulingame,e cells formed CA, a bridge USA) and followedacross using the inner diaminobenzidine sides of tubules. (DAB). H&E staining. Immunohistochemical Bar = 50 μm. (D analysis) Well-differentiated revealed that Sertoli the neoplasm cells was positiveshowing forround-to-oval vimentin (Figure nuclei forming3A) and irregular ER- β immunoglobulins shaped tubules (indicated (Figure 3byB), arrow). whereas H&E cytokeratin staining. 19, S-100,Bar and = 50 inhibin- μm. α were negative.

Figure 3. Immunohistochemical properties of Sertoli cell tumor isolated from the testicle of a black bear. (A) All tumor cells showed very strong positive reaction to vimentin immunoglobulins. Bar = 100 μm. (B) Numerous Sertoli cells showed a strong positive reaction to ER-β. Bar = 100 μm.

3. Discussion

Sex cord stromal tumors are a rare testicular tumor, accounting for 4% of all testicular neoplasms Figure 3. Immunohistochemical properties of Sertoli cell tumor isolated from the testicle of a black bear. of humanFigure adult 3. Immunohistochemical males. Sertoli cell tumors properties have of a Sertolilower cellprevalence, tumor isolated representing from the 0.4 testicle–1.5% of of a testicularblack (A) All tumor cells showed very strong positive reaction to vimentin immunoglobulins. Bar = 100 µm. neoplasmsbear. ([7].A) All Sertoli tumor cell cells tumors showed are very common strong positivein elder reaction or cryptorchid to vimentin dogs immunoglobulins. [8,9]. Generally, Bar Sertoli = (B) Numerous Sertoli cells showed a strong positive reaction to ER-β. Bar = 100 µm. cell tumors100 μm. are (B benign.) Numerous However, Sertoli cells a few showed reports a strong have positivedescribed reaction malignancy to ER-β .in Bar dogs = 100 [8,10,11]. μm. 3. DiscussionIn the literature, only nine neoplasms have been reported in the Ursidae family, but none of them3. Discussion were observed in the testicles. Moreover, the bear was in captivity, subjected to disease monitoringSex cord and stromal exhibited tumors no signs are a rareon unexpected testicular tumor, death accounting at the age forof 29. 4% The of all testicular testicular tumor neoplasms was Sex cord stromal tumors are a rare testicular tumor, accounting for 4% of all testicular neoplasms discoveredof human adultduring males. necropsy Sertoli examination cell tumors and have was a lower unlik prevalence,ely to be the representing cause of death. 0.4–1.5% No one of testicularfamiliar of human adult males. Sertoli cell tumors have a lower prevalence, representing 0.4–1.5% of testicular withneoplasms the animal [7]. Sertoli observed cell tumors any signs are common of feminization in elder or cryptorchidor alopecia, dogs which [8,9 ].are Generally, common Sertoli clinical cell neoplasms [7]. Sertoli cell tumors are common in elder or cryptorchid dogs [8,9]. Generally, Sertoli manifestationstumors are benign. of Sertoli However, cell tumors. a few reports Lack of have these described signs could malignancy be owing in to dogs solitary [8,10 ,captivity11]. of the cell tumors are benign. However, a few reports have described malignancy in dogs [8,10,11]. bear because feminization is most evident in the presence of another animal and is based on the In the literature, only nine neoplasms have been reported in the Ursidae family, but none of interaction between the two animals. them were observed in the testicles. Moreover, the bear was in captivity, subjected to disease monitoring and exhibited no signs on unexpected death at the age of 29. The testicular tumor was discovered during necropsy examination and was unlikely to be the cause of death. No one familiar with the animal observed any signs of feminization or alopecia, which are common clinical manifestations of Sertoli cell tumors. Lack of these signs could be owing to solitary captivity of the bear because feminization is most evident in the presence of another animal and is based on the interaction between the two animals. Vet. Sci. 2019, 6, 77 4 of 5

In the literature, only nine neoplasms have been reported in the Ursidae family, but none of them were observed in the testicles. Moreover, the bear was in captivity, subjected to disease monitoring and exhibited no signs on unexpected death at the age of 29. The testicular tumor was discovered during necropsy examination and was unlikely to be the cause of death. No one familiar with the animal observed any signs of feminization or alopecia, which are common clinical manifestations of Sertoli cell tumors. Lack of these signs could be owing to solitary captivity of the bear because feminization is most evident in the presence of another animal and is based on the interaction between the two animals. In dogs, the expression proﬁle of Sertoli cell markers were predominantly consistent with testicular neoplasms [12–14]. Canine Sertoli cell tumors express vimentin but not cytokeratin, desmin, or inhibin-α [12,14]. In the present case, Sertoli cell showed a strong expression of vimentin in all parts of the neoplasm, whereas cytokeratin 19 and inhibin-α were negative. Interestingly, this expression pattern is consistent for Sertoli cell tumors in dogs. Sertoli cell within the bear’s neoplasm showed a strong positive expression for ER-β. This could be explained by the absence of inhibin-α expression, which regulates paracrine function of testicles by inhibiting follicle stimulating hormone and subsequently preventing estradiol expression [15].

4. Conclusions To the author’s knowledge, this is an uncommon case of Sertoli cell tumors in an American black bear.

Author Contributions: A.K.E., S.P., H.M.A.U., S.-H.Y., M.-J.C., J.-Y.S., J.-E.L., S.-W.L., A.-R.L., S.-M.B., S.-G.J., E.-J.L. and I.-H.H. involved in this experiment; A.K.E., and H.M.A.U., wrote the paper; J.-K.P. and K.-S.J. reviewed and edited the manuscript. J.-K.P. and K.-S.J. supervised the case. All authors (A.K.E., S.P., H.M.A.U., S.-H.Y., M.-J.C., J.-Y.S., J.-E.L., S.-W.L., A.-R.L., S.-M.B., S.-G.J., E.-J.L., I.-H.H. and J.-Y.L.) approved the final manuscript. Funding: This research supported by the National Research Foundation of Korea (NRF-2017R1E1A1A01072781). Conflicts of Interest: The authors declare no conflict of interest.

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