Spontaneous Zymbal's gland tumor in a 25-week old Wistar male rat

This work describes a spontaneous Zymbal’s gland tumor in a 25-week old Wistar male rat that had been included in the control sedentary group of an assay of hormone and chemically-induced prostate cancer. The animal exhibited a unilateral, round, ulcerated mass, ventral to the left ear. Histopathologically, it was a non-encapsulated mass composed of solid sheets of basaloid epithelial cells with occasional sebocyte differentiation. Multiple cells presented variable sized eosinophilic granules. The histopathological data were compatible with a basaloid carcinoma, and its location is suggestive of Zymbal’s gland (auditory sebaceous gland) origin.