Summary 1.A brief review of the literature is given, emphasising that dissimilarity in histological appearance represents merely variation in differentiation and maturity. 2.Three illustrative cases are presented. 3.In one of these, already reported in 1934, treatment by removing the superficial part of the tumours and enucleating from the dermis produced a pleasing result. 4.A hitherto unreported association of epithelioma adenoides cysticum with generalised neurofibromatosis is described.