Cutaneous apocrine mixed tumor: derived from the apocrine duct of the folliculo-sebaceous-apocrine unit?

We report a case of cutaneous mixed tumor (CMT) composed of tubular branching structures lined by cells with apocrine characteristics. In addition, an apocrine duct in the outer sheath of an hair follicle was connected to the mixed tumor, a previously unreported finding. Follicular and sebaceous differentiation have been described in CMT, leading some observers to suggest the existence of an apocrine type of CMT and its presumed differentiation toward the folliculo-sebaceous-apocrine unit (FSAU). Our case demonstrated continuity of an apocrine duct in the FSAU and lends support to the previous speculations about the histogenesis of apocrine type of CMT.