Thymoma associated with exfoliative dermatitis in a cat.

A 7-year-old, castrated male, domestic shorthair cat presented with generalized exfoliative dermatitis, lethargy, anorexia and weight loss. Multiple skin scrapings taken at the time did not reveal any abnormalities. Skin histopathological examination was consistent with sebaceous adenitis or exfoliative dermatitis caused by an underlying thymoma (thymoma-associated feline exfoliative dermatitis). Thoracic radiographs revealed a cranial mediastinal mass, which was removed surgically. Histopathological examinations indicated that it was a thymoma. Within 90 days of surgery, the cutaneous signs had resolved, suggesting a causal relationship between the thymoma and the skin disease. Recurrence of thymoma was detected 24 months after surgery.