Among all species, dog have more incidences and contribute about 90% of all male genital tumours¹. Testicular tumours are one of the most frequent occurring genital neoplasm come across in male dogs, particularly sertoli cell tumours, seminoma and leydig cell tumours. Seminoma are considered as germ cell tumour of the testis² and commonly encountered in aged male dogs³. A major feature of seminoma is mostly unilateral but occasionally bilateral. In veterinary medicine, canine seminoma is uncommonly subdivided³ into two types that are morphologically consistent with human spermatocytic seminoma and classical seminoma². Usually, seminomas are associated with cryptorchidism⁴. Seminoma are most frequently encountered in right testicle and noted as scrotal enlargement. However, few cases are reported on seminoma without association with cryptorchid⁵. The present case is an attempt to document the cytological as well as histopathological features of seminoma in a non-cryptorchid dog.

A fourteen-year-old non-descript male dog was presented to the Small Animal Multispecialty Clinics of Department of Teaching Veterinary Clinical Complex, GADVASU, Ludhiana with the history of lethargy, anorexia, vomition, polyuria and testicular enlargement since last three months. Clinical examination of dog revealed dull and depressed appearance. However, lymph nodes did not reveal any enlargement. On palpation, right testicle revealed unilateral enlargement (Fig. 1) but non-cryptorchid. X-ray and ultrasonography were performed to rule out metastasis or any abdominal growth. For further confirmation, the impression smear from abnormal mass was prepared and stained with Leishman stain for cytological examination. Then punched biopsy of right testicle was taken for histopathological examination, fixed tissue in 10% formalin, and processed for routine paraffin sectioning. In addition, blood and serum samples were collected for hematology and biochemical examination (alanine aminotransferase (ALT), total bilirubin, serum albumin, blood urea nitrogen (BUN), creatinine and serum phosphorus).

Hematological examination showed mild anaemia, absolute neutrophilia and lymphopenia (Table no. 1) when compared with the reference values (Reference). Similar hematological findings had been reported^6,7. Biochemical parameters revealed elevated ALT, BUN and creatinine (Table no. 2) when compared with the reference values (Reference). This was in contrary to the findings of earlier report who observed all values were within range in a case of seminoma⁷. In present study, elevated serum biochemical values might be due to old age related decrease in the organ function.

Impression smear of given mass revealed high cellularity of large, discrete, round cells showing reticular chromatin pattern (coarse chromatin) with large round nuclei and prominent eosinophilic nucleoli (Fig 2). Few mature lymphocytes along with round cells and mitotic figures (Fig 3) were also observed representing the hallmark of seminoma². Multinucleation was also common (Fig 4). Similar cytological findings were also described by earlier reports^6,8.

On histopathology, diffuse anaplastic cells forming broad sheets with some necrosed area and few mitotic figures were observed (Fig 5). Large neoplastic cells having large vesicular nuclei, prominent nucleoli, and scant basophilic cytoplasm along with frequent mitotic figures (Fig 6). These histological findings confirms physical and cytological examination, which were similar to the earlier reports^9,10.

Earlier reports of seminoma in dogs were recorded mostly in aged dogs, which are considered as predisposing factor³, similar to the present case of fourteen years old dog. In present case, unilateral, solitary involvement of the right testis was identified which were similar to earlier findings^11,12. However, it was also reported that 50% of dogs affected with testicular tumours had bilateral involvement¹². In this report, dog with seminoma did not have cryptorchidism, which is common occurrence in testicular tumour according to several literatures^4,14. The present report of seminoma without cryptorchidism was similar to recent finding⁵.

Thus, the present case reports the diagnosis of seminoma in a non-cryptorchid male dog on the basis of physical, cytological and histopathological examination.

References