What is a positive “dimple” sign?

Dermatofibromas are considered to be benign fibrohistiocytic tumors that do not demonstrate a malignant potential. Though dermatofibromas share clinical and some general histologic similarities with a malignant neoplasm called dermatofibrosarcoma protuberans, histochemical markers show the two are distinct. Although the dermatofibroma itself does not progress into malignancy, the overlying epidermis demonstrates a slight risk to develop into basal cell carcinoma.