[Seborrheic keratosis on the umbilicus: case report and review of Japanese literature].

ABSTRACT

A 78-year-old man was seen for a tumor on his umbilicus. Clinically, there was a dark brown nodule with thick scales. The excised tumor showed the acanthotic type of seborrheic keratosis. Six cases of seborrheic keratosis arising on the umbilicus have been reported. All of them were of the histologically hyperkeratotic type. Our case is the first report of an acanthotic type of seborrheic keratosis on the umbilicus. Seborrheic keratosis is one of the common skin tumors, but we hesitated in this diagnosis because of its abnormal location.