Seborrheic Keratosis With Prominent Clear Cell Changes—A Rare But Important Diagnostic Variant
Seborrheic keratoses, although exceedingly common, occasionally have morphologic similarities to other lesions that complicate a typically straightforward diagnosis. The authors present a case of a 69-year-old man with a left shoulder lesion that displayed characteristic clinical and microscopic features of seborrheic keratosis on biopsy. However, diffuse and prominent clear cells were also noted. These stained strongly with Periodic acid–Schiff and were diastase sensitive, suggestive of glycogen accumulation and possible trichilemmal differentiation. This case is presented to demonstrate a unique and striking example of clear cell change within a seborrheic keratosis and to briefly review the published literature on this finding, which is rarely reported and demands close examination to exclude more aggressive neoplasms.