TESTICULAR EFFERENT DUCTULE CYST OF A DOG

A 9-year-old male Shetland Sheepdog had a small mass in the left testi s. Grossly, the round to oval cyst was present at the upper pole of th e testicular parenchyma near the head of the epididymis. Histologicall y, the cyst was lined by a single layer of nonciliated and ciliated ep ithelial cells. Immunohistschemically, the epithelial cells of the cys t showed expression of the low- and high-molecular-weight cytokeratins , vimentin, and desmin similar to that of normal efferent ductules in the dog. The testicular cystic dysplasia was thought to originate from the efferent ductules.