Hyperkeratotic lichenified skin lesion of gluteal region.

Elderly people may develop typical skin lesions on the superior part and both sides of the anal cleft. Although such skin changes have recently been reported as anosacral cutaneous amyloidosis in primary cutaneous amyloidosis, in our histopathological examinations no amyloid deposition has been detected at the sites of these lesions. Because hyperkeratosis, acanthosis and follicular plugging were seen in all of the cases histopathologically, we think that these skin manifestations are essentially a type of keratinization abnormality instead. We consider this disease to be a type of senile skin change that develops in response to prolonged mechanical irritation.