Histiocytoma, Sclerosing angioma
The dermatofibroma is a benign proliferation of fibroblasts in association with an increased number of mast cells and, often, blood vessels.
Clinically, the lesion is a tethered, firm, intracutaneous nodule of 0.5 to 2 cm in diameter, often with associated hyperpigmentation in the overlying skin.
If rubbed, urtication from mast cell release of mediators can occur.
Because of the tethering, squeezing the lesion results in a central umbilication, the dimple sign.
If bothersome to the patient, the lesion can be excised.