Skin, Seborrheic keratosis, clonal subtype

Seborrheic keratosis (SK) is a common, benign lesion and comes in many variations. In this variation, the cells are notable for strikingly monotonous morphology, with intra-epidermal nests of oval to round cells. The term “clonal” is used in this setting to describe this appearance.

While distinction of clonal SK from squamous cell carcinoma may be challenging, the absence of mitoses high in the epidermis is reassuring.