Multiple Cutaneous Metastasis of a Malignant Leydig Cell Tumour in a Dog.

A testicular Leydig cell tumour associated with metastatic disease is reported in a dog. An enlarged testis and three cutaneous nodules resected from an 11-year-old golden retriever were submitted for histopathological examination. Both testicular and cutaneous lesions showed identical morphological and cytological changes. Immunohistochemical labelling for expression of inhibin-α and calretinin confirmed the Leydig origin of the cutaneous neoplastic population. Based on the morphological and immunohistochemical findings, a final diagnosis of multiple cutaneous metastasis of a malignant testicular Leydig cell tumour was made.