Seborrheic keratoses in five elderly patients: an appearance of raindrops and streams.

Five Chinese patients were found to have a linear, splayed, vertical pattern of lesions on their back, chest and abdomen. These lesions were clinically and pathologically diagnosed as seborrheic keratosis. The mean age of our patients was 77.6 years. During the follow-up period of 12-20 years, the lesions appeared to increase with age, and no malignant changes were observed on these sites. These patients had no serious underlying medical problems or malignant neoplasm, except for one patient with duodenal ulcer. While we are uncertain as to the cause of this patterning of seborrheic keratoses, we believe that it is distinct from previously reported patterns; this will contribute to research on the pathogenesis of seborrheic keratosis.