Hidroacanthoma simplex (HAS), also known as intraepidermal
eccrine poroma, is a rare eccrine adnexal
tumor that tends to be misdiagnosed as other types of benign skin
tumor, including clonal
seborrheic keratosis. Notably, HAS is sometimes misdiagnosed and treated by
cryosurgery as
seborrheic keratosis, which could trigger the later development of porocarcinoma. Therefore, accurate diagnosis of HAS is indispensable for dermatologists to avoid the development of malignant
tumors by an unsuitable treatment. In this report, we present the characteristic dermoscopy findings of HAS. Indeed, the dermoscopy findings might be related to the
melanin-rich necrotic cells in the epidermis, which are quite different from dermoscopy findings of clonal
seborrheic keratosis. As a previous report suggested, it is difficult for a dermatologist to differentiate HAS from clonal
seborrheic keratosis by the naked eye. Our findings might be supportive for the early diagnosis of HAS.