Sertoli cell tumor in an alpaca

A 9 year old intact male alpaca was presented with a unilaterally enlarged right testis that the owner noticed after annual shearing. He had no previous breeding history, nor history of health or behavioral problems. Physical examination was normal except for visible unilateral scrotal enlargement. Scrotal palpation findings were, a large turgid right testis and a soft left testis, with normal epididymides. Palpation elicited no pain response and ruled out the presence of epididymitis, herniation, or testicular torsion. Testicular ultrasonography revealed a heterogeneous appearance of right testis parenchyma with diffuse multifocal areas of hyperechoic foci and several anechoic pockets. Left testis was comparatively homogenous in appearance with rare hyperechoic foci. At this point, differential diagnoses included neoplasia or orchitis. A bilateral elective castration was performed, since this alpaca was not intended for breeding. After castration, right testis measured 50 x 54 mm, with 2 cystic structures and a bulging cream-colored bulging structure grossly identified upon dissection. Left testis measured 37 x 32 mm with no gross abnormalities. Histopathology diagnosed a Sertoli cell tumor that completely replaced the stroma in the right testis and diffuse degeneration with no tumor infiltration in left testis. Spermatic cord was also free from tumor involvement. The alpaca recovered from castration uneventfully. Testicular neoplasia in camelids is rare. While Sertoli cell tumors have been reported in dogs, bulls, rams, cats, and horses, apparently, this is the first report in camelids. Sertoli cell tumors are characteristically hormonally active. While no symptoms were present in this case, degeneration of contralateral testis suggested that the tumor might have been secreting estrogen. Bilateral castration proved to be curative for this alpaca; however, since no metastasis was evident, unilateral castration might have preserved fertility, if there was an intention to use the animal for breeding.

Keywords: Sertoli cell tumor, testicular enlargement, testicular degeneration, alpaca

References

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This manuscript was originally published in the journal Clinical Theriogenology Vol 12(3) Sept 2020.  Clinical Theriogenology is the official journal of the Society for Theriogenology (SFT) and the American College of Theriogenologists (ACT).  This content has been reproduced on the IVIS website with the explicit permission of the SFT/ACT.