A case of Bowen's disease arising in seborrheic keratosis

Seborrheic keratosis is a benign epidermal neoplasm, but malignant transformation may, rarely occur. We, herein, report an unusual case of Bowen's disease arising in seborrheic keratosis. A 74-year-old man presented with multiple grouped erythematous to dark brownish papules on the left shoulder for 9 months. Histopathologic examination taken from the largest papule of the left shoulder revealed the findings of seborrheic keratosis connecting with Bowen's disease. This case supports the possibility of malignant transformation of seborrheic keratosis.