Malignant Leydig cell tumor in dogs: two cases and a reviewof the literature

摘要

Malignant Leydig cell tumor (MLCT) is a rare testicular tumor in dogs. Wereport herein 2 dogs with MLCT and cutaneous metastasis. Grossly,marked enlargement and distortion of the involved testes were noted;on cut surface, the parenchyma was completely replaced by neoplastictissue. In addition, these tumors had extensive necrosis andhemorrhage. Case 1 had a rapidly growing cutaneous mass in the leftangle of the mouth; the lesion was well-circumscribed and had anindistinct lobular pattern. Case 2 had multiple cutaneous masses inthe dorsal neck region, the thoracic back region, and the righthindlimb. Microscopically, the tumor lobules were composed ofoval-to-polyhedral cells with eosinophilic cytoplasm and resembledtesticular tumors. By immunohistochemistry, the neoplastic cells inboth the testicular and cutaneous tumors were positive forinhibin-alpha and melan A. The mitotic counts of the primary tumorsfrom cases 1 and 2 were 21 and 11 per 10 high-power fields,respectively. Based on these findings, the cases were diagnosed asMLCT with cutaneous metastasis. Ki-67 expression in the neoplasticcells of the 2 cases was higher than in benign Leydig cell tumors. Ourfindings may be helpful for the diagnosis of canine MLCT.