The case of a 63-year-old man with acrosyringeal adenomatosis (eccrine syringofibroadenoma of Mascaro) is reported. Asymptomatic papular lesions had appeared on the dorsum of both of his feet 30 years earlier, then extended gradually and symmetrically to his hands, arms, legs, trunk, and auriculae. Although his hair, teeth, and nails were normal, he had glaucoma, chronic sinusitis, chronic otitis media, chronic pancreatitis, and gastrointestinal polyposis. No similar symptoms were found in the family history. Histopathologically, proliferations of pale epithelial cells extended from acrosyringia into the dermis, forming interconnected epithelial cords, within some of which were ductal structures. A syringoma and syringoma-like structures were closely associated with these lesions. Enzyme-histochemical, immunohistochemical, and ultrastructural studies supported the concept that this case represents a benign tumor derived from the acrosyringium, which is different from eccrine poroma. Acrosyringeal adenomatosis seems to be a more appropriate name for such a lesion than does eccrine syringofibroadenoma (Mascaro).