Scrotal calcinosis: origin from dystrophic calcification of eccrine duct milia.

Scrotal calcinosis is a rare benign disorder considered idiopathic by most recent authors, although an origin from dystrophic calcification of epidermoid cysts has been proposed. In 3 of 4 cases which were otherwise typical of scrotal calcinosis, there was calcification of the contents of small cysts lined by stratified squamous epithelium. These structures were identified as eccrine duct milia because some of them communicated with eccrine ducts and there were ultrastructural features of eccrine duct differentiation in one case. The eccrine nature of the milia was confirmed using the immunoperoxidase technique for the demonstration of carcinoembryonic antigen (CEA) which serves as a marker of eccrine sweat glands. Since a transition could be seen between degenerating calcified milia and typical nodules, it appeared that the calcific deposits of scrotal calcinosis result from the breakdown of such lesions. Staining of deposits unassociated with cyst walls with the technique for the demonstration of CEA supported this conclusion. An advanced stage of evolution of the disease could account for the absence of visible cysts in many cases. We propose the term "hidrocalcinosis of the scrotum" for this distinctive form of cutaneous calcification.