A tumor derived from eccrine sweat duct epithelium which may be intra-epidermal (hidro-acanthoma simplex), juxta-epidermal (eccrine poroma) or intradermal (dermal duct tumor). They are comparatively uncommon. There is no indication that heredity or external agents cause these tumors. (Rook et al., Textbook of Dermatology, 4th ed, p2409).
