[Hereditary progressive mucinous histiocytosis]

Hereditary progressive mucinous histiocytosis is an uncommon condition which to date has only been observed in women. The disease is a non-Langerhans histiocytosis with a stereotypic clinical presentation limited to the skin. The clinical, histological and genetic features of this disease differ considerably from other types of histiocytoses and overload diseases. We report the first case observed in France.

A 49-year-old woman consulted for asymptomatic papules on the dorsal aspect of the hands known since childhood. The lesions had progressively spread to other regions of the body. The woman's mother and two sisters had the same condition but her two sons and her brother and nephews did not. Standard semi-thin slices and electron microscope histology demonstrated dense cellular infiltration of the reticular dermis with interstitial mucinous overload, voluminous histiocytes with characteristic toluidine blue positive granulations, and a cytoplasm rich in myelin and Zebra bodies respectively. The observed clinical, histological and genetic features were characteristic of progressive hereditary progressive mucinous histiocytosis.

The pedigree in our case and in those reported in the literature suggest a dominant hereditary condition. The fact that only female cases have been reported to date would suggest X-linked transmission with early death of male fetuses. An autosomal dominant transmission limited to woman as a result of mitochondrial heredity or hormone-related phenomena cannot be ruled out. The progressive extension with age without a tendency for spontaneous regression and the electron microscopy aspect suggest a phospholipid deposit disorder similar to that observed in lysosomial diseases. However, primary macrophage proliferation in response to an unknown stimulus cannot be excluded.