A canine testicular tumor resembling gonadoblastoma

Canine ovarian gonadoblastoma with dysgerminoma overgrowth: a case study and literature review

BACKGROUND

Gonadoblastoma (GB) is a rare mixed germ cell-sex cord-stromal tumour, first described in humans, commonly found in dysgenetic gonads of intersex patients that have a Y chromosome. However, this entity in not recognized in the WHO classification of tumours of genital system of domestic animals. Herein, we describe a case of ovarian gonadoblastoma with proliferation of dysgerminoma and sex cord-stromal tumour components, in a phenotypically and cytogenetically normal bitch.

CASE PRESENTATION

A 17-year-old cross-breed bitch had a firm, grey-white multinodular mass in the left ovary. The tumour was submitted to histopathological examination and Y chromosome detected through karyotype analysis and PCR studies. Microscopically, the ovary was almost replaced by an irregular neoplasm composed of three distinct, intermixed elements: dysgerminoma, mixed germ cell-sex cord-stromal tumour resembling human GB and a proliferative sex cord-stromal tumour component. The germ cells of gonadoblastoma and dysgerminoma components were immunoreactive for c-KIT. Sex cord-stromal cells of gonadoblastoma were immunoreactive for α-inhibin. The sex cord-stromal tumour was immunoreactive for AE1/AE3, occasionally for α-inhibin and negative for epithelial membrane antigen (EMA). The karyotype was 78, XX and PCR analysis confirmed the absence of the Y chromosome.

CONCLUSION

Based on these findings, a diagnosis of gonadoblastoma with proliferation of dysgerminoma and sex cord-stromal tumour was made. This is the first case of ovarian gonadoblastoma in a female dog.

Histologic and Immunohistochemical Characterization of a Testicular Mixed Germ Cell Sex Cord-Stromal Tumor and a Leydig Cell Tumor in a Dog

Mixed germ cell sex cord-stromal tumors (MGSCTs) of the testis are rare in dogs. We describe the histopathology and immunohistochemical characteristics of an MGSCT associated with a Leydig cell tumor in a cryptorchid testis. Histologically, MGSCT consisted of two nodules of seminiferous tubules lined by germ cells and Sertoli cells in variable proportions. Germ cells had variable size and nuclear features, with frequent giant cells. Germ cells were evenly mixed with Sertoli cells or located in the center of tubules. Markers that labeled mainly germ cells and few or no Sertoli or Leydig cells were calretinin, KIT, and PGP 9.5. E-cadherin, GATA-4, inhibin-α (INH-α), and neuron-specific enolase (NSE) were predominantly detected in Sertoli cells, whereas melan A was particularly expressed in Leydig cells and vimentin in all three cell types. OCT3/4 was not detected in any cell type. Although more cases of canine MGSCT need to be examined, our results suggest that an immunohistochemical panel of E-cadherin, GATA-4, INH-α, KIT, NSE, PGP 9.5, and melan A will help distinguish the three main cell types in canine testicular germ cell and sex cord-stromal tumors.

Onco-epidemiology of domestic animals and targeted therapeutic attempts: perspectives on human oncology

The spontaneous tumor biology has been investigated with the support of animalists using animals as a preclinical model allowing translation of results in clinical practice. This review provides an insight into the field of comparative oncology. Evidence shows that companion animal health care is impressively growing in terms of development of new therapies and diagnostic tools, nutrition and disease prevention. However, even if most animal tumors might be a reliable model to study human carcinomas, many open questions, related to the opportunities to select and recruit new models in oncology, along with their legal and ethical implications, remain unanswered.

Gonadoblastoma in the ovaries of a lesser galago (Galago senegalensis braccatus)

An enlarged right ovary was removed from a 14-year-old lesser galago (Galago senegalensis braccatus). Cytological preparations consisted of a heterogeneous population of neoplastic cells admixed with extracellular hyaline structures and cell-free nuclei. Microscopically, the ovary was replaced with gonadoblastoma and was composed of nests of germinal cells, including large oocyte-like cells, and sex cord-stromal cells arranged in palisading patterns around the germinal cells, the periphery of the nests and around extracellular hyaline material. The animal died 2 years after initial diagnosis. Necropsy examination revealed gonadoblastoma in the left ovary. The germinal cells of the tumour in the right and left ovaries were immunoreactive for calretinin, OCT3/4, PGP 9.5, Ki67 and/or faintly for cytokeratins. Sex cord-stromal cells were immunoreactive for calretinin, OCT3/4, GATA-4, E-cadherin and vimentin. Luteinized sex cord-stromal cells were immunoreactive for inhibin-alpha. The extracellular hyaline material was immunoreactive for laminin. This is the first case of gonadoblastoma in a non-human primate.

Testicular gonadoblastoma in two pet domestic rabbits (Oryctolagus cuniculus domesticus)

Testicular gonadoblastoma is an uncommon tumor in domestic animals. The current study describes a testicular gonadoblastoma in 2 pet domestic rabbits ( Oryctolagus cuniculus domesticus) based on the histomorphological, immunohistochemical, and ultrastructural characteristics of the tumor. The tumor tissue consisted of discrete tubular structures separated by a fibrous stroma. The tubular structures were composed of large round cells similar in appearance to germ cells in the seminiferous tubules, and small spindle cells with oval or elongated nuclei resembling Sertoli cells. The spindle cells showed peculiar structural patterns arranged in a coronal or follicular pattern, often forming Call–Exner bodies like those in an ovarian granulosa cell tumor. One case was concomitant with seminoma. Immunohistochemistry revealed large round cells that were positive for c-kit and placental alkaline phosphatase, while spindle cells were positive for vimentin and Wilms tumor protein. Ultrastructurally, the spherical eosinophilic material (Call–Exner body) consisted of duplicated basal lamina, and sex cord components surrounded a single degenerative cell similar to a germ cell.

Biphasic malignant testicular sex cord-stromal tumor in a cotton-top tamarin (Saguinus oedipus) with review of the literature

A 20-year old male cotton-top tamarin (Saguinus oedipus) was presented with unilateral enlargement of an intrascrotal testicle. Fine-needle aspiration cytology demonstrated a neoplastic population with Call-Exner-like bodies and features of malignancy. The animal was castrated, and histologic examination revealed a biphasic sex cord-stromal tumor, with one region resembling Sertoli-cell tumor and one region resembling granulosa-cell tumor, with extensive microfollicular pattern and many Call-Exner bodies. Eight months after castration, the animal was euthanized on discovery of a caudal abdominal mass that displaced organs, was highly infiltrative, and extended into the paravertebral musculature with lysis of vertebral bone. Metastases to lymph node and lung were also present. Histologic examination of the abdominal tumor showed multifocal formation of Call-Exner bodies in an otherwise highly dedifferentiated population. Positive immunolabeling for alpha inhibin confirmed the sex cord-stromal origin of the abdominal and paravertebral tumor masses. This case has similarities to malignant testicular granulosa-cell tumor of humans.

Cytological features of canine ovarian tumours: a retrospective study of 19 cases

The cytological features of 19 histologically confirmed canine ovarian tumours were retrospectively examined. Seven cases were cytologically classified as papillary adenocarcinoma, eight cases as granulosa cell tumours, two cases as mature ovarian teratomas, one case as a dysgerminoma and one case as a mixed granulosa cell tumour/dysgerminoma. On cytology, papillary adenocarcinoma was characterised by a papillary glandular pattern and tight cohesiveness. Granulosa cell tumours showed monolayered clusters of loosely cohesive granulosa cells. Call-Exner-like bodies were found in five of seven cases. Granulosa cells appeared to be heterogeneous and usually contained several intracytoplasmic vacuoles. Teratoma was characterised cytologically by keratin debris (two cases) and a mixture of epithelial cells with sebaceous, basaloid, columnar/palisading or ciliated appearance (one case). The dysgerminoma contained severely atypical round cells admixed with small lymphocytes. The mixed dysgerminoma/granulosa cell tumour had a mixture of germinal and granulosa cells. Cytological diagnosis was in agreement with histopathology in 18 of 19 (94.7 per cent) cases.

Rete testis mucinous adenocarcinoma in a dog

A bilateral testicular neoplasm from an 11-year-old mixed-breed male dog was removed surgically and examined histologically. The neoplasm was nonencapsulated and composed of acinar and tubular structures lined by one or more layers of neoplastic polyhedral epithelial cells with an abundant mucinous secretion. On histochemistry, all neoplastic cells and associated secretions were periodic acid-Schiff positive. Some neoplastic cells and all associated secretions were positive on mucicarmine stain, and some neoplastic cells, all the stroma, and associated secretions were positive on alcian blue stain. On immunohistochemistry, the neoplastic cells had strong diffuse cytoplasmic immunoreactivity for cytokeratin and vimentin, weak scattered cytoplasmic immunoreactivity for carcinoembryonic antigen and neuron-specific enolase, and no immunoreactivity for S-100. On the basis of histopathology, histochemistry, and immunohistochemical findings, a diagnosis of mucinous adenocarcinoma of rete testis was made. Rete testis adenocarcinoma is a well known but very rare neoplasm in humans. To our knowledge, this is the first report of the mucinous variant of adenocarcinoma of the rete testis in a dog.

Bilateral Gonadoblastomas in a Dog with Mixed Gonadal Dysgenesis

Gonadoblastomas are rare mixed germ cell neoplasms, which are frequently diagnosed in testes excised for other reasons. In human patients these tumours are usually associated with undescended testes or dysgenetic gonads. This report describes a 10-year-old male dog with mixed gonadal dysgenesis ("streak testis" on the right side and testis on the left side) and bilateral gonadoblastomas. Immunohistochemical analysis revealed an atypical and mitotically active germ cell population which co-expressed placental alkaline phosphatase and c-kit oncogene, admixed with inhibin- and S-100 protein-positive sex cord cells. The findings were generally consistent with previous reports of the dual population of neoplastic cells in gonadoblastomas affecting human patients, and closely resembled the findings in the only other case reported in dogs. Moreover, the findings further support the proposal that gonadoblastomas should be considered a special form of in-situ germ cell neoplasia.

Sertoli cell tumour with Call-Exner-like bodies in a dog

An histological diagnosis of Sertoli cell tumour and concurrent seminoma was formulated after complete resection of the right testicle in a 8-year-old Doberman. The unusual histological feature of abundant eosinophilic material with a extracellular location forming the Call-Exner-like bodies is reported.

Ovarian sex cord-stromal tumours in cattle, with particular reference to the lamination of basal laminae

Three cases of bovine sex cord-stromal tumours, including a sex cord tumour with annular tubules and two granulosa cell tumours, are described. These tumours had tubular structures and hyaline or eosinophilic bodies, composed of multilayered basal laminae. The present study suggests that bovine granulosa cell tumours of the ovary are able to show morphology similar to that of Sertoli cell tumours of the testis and that sex cord tumours with annular tubules arise from granulosa cells but indicate Sertoli cell differentiation.

A clinicopathologic, histologic, and immunohistochemical study of mixed germ cell-stromal tumors of the testis in 16 dogs

In a review of 262 neoplasms in 225 dogs, 18 tumors in 16 dogs were mixed germ cell-stromal tumors containing intimately admixed germ cells and Sertoli cells in tubular structures of various sizes. Seven of the 18 neoplasms were predominantly composed of germ cells, and 11 were predominantly composed of Sertoli cells. In 15 neoplasms, the germ cells were more anaplastic than the Sertoli cells, and in three neoplasms, both cell types were anaplastic. Five of the seven mixed-cell tumors with predominantly germ cells had germ cells infiltrating the adjoining tissues. Immunocytochemical studies of all 18 mixed-cell tumors, testes from five clinically normal dogs, six seminomas, and six Sertoli cell tumors revealed that neuron specific enolase (NSE) and vimentin were useful in demonstrating the dual population of the mixed cell tumors by differential staining of the germ cells and Sertoli cells. Half of the tumors stained differentially with desmin. In the normal testes, seminomas, and Sertoli cell tumors, parallel staining of germ cells and Sertoli cells by NSE and vimentin was seen, but only the appropriate tissues stained with desmin. The mixed-cell tumors in this study had morphologic features in common with mixed germ cell-sex cord stromal tumors and gonadoblastomas of human beings; clinically, they had more in common with the former. These mixed cell tumors in dogs should be classified separately.