Seborrheic keratoses: appearance in course of exfoliative erythroderma and regression associated with histologic mononuclear cell inflammation.

We observed a patient in whom large numbers of seborrheic keratoses developed in the course of a generalized dermatitis that progressed into an exfoliative erythroderma. A renal mass was finally discovered and was surgically excised. On microscopic examination, the kidney tumor proved to be a benign fibrous-walled, multilocular cyst. After removal of the renal cyst, the erythroderma and exfoliation subsided. A few months later, the seborrheic keratoses were noted to have become smaller, flatter, and fewer in number. Microscopic examination of five such involuting lesions showed, in each instance, mononuclear cell infiltration of the seborrheic keratoses. Our findings confirm earlier reports that seborrheic keratosis-like lesions developing during the course of widespread inflammatory cutaneous disorders may regress after control of the dermatosis and suggest that mononuclear cell inflammation may be the mechanism by which regression of these lesions is accomplished.