Hereditary progressive mucinous histiocytosis.

Background. Hereditary progressive mucinous histiocytosis is an uncommon co ndition 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 diseas e differ considerably from other types of histiocytoses and overload diseas es. We report the first case observed in France. Case report. A 49-year-old woman consulted for asymptomatic papules on the dorsal aspect of the hands known since childhood. The lesions had progressi vely spread to other regions of the body. The woman's mother and two sister s had the same condition but her two sons and her brother and nephews did n ot. Standard semi-thin slices and electron microscope histology demonstrate d dense cellular infiltration of the reticular dermis with interstitial muc inous overload, voluminous histiocytes with characteristic toluidine blue p ositive granulations, and a cytoplasm rich in myelin and Zebra bodies respe ctively. The observed clinical, histological and genetic Features were char acteristic of progressive hereditary progressive mucinous histiocytosis, Discussion. The pedigree in our case and in those reported in the literatur e suggest a dominant hereditary condition. The fact that only Female cases have been reported to date would suggest X-linked transmission with early d eath of male fetuses. An autosomal dominant transmission limited to woman a s a result of mitochondrial heredity or hormone-related phenomena cannot be ruled out. The progressive extension with age without a tendency for spont aneous 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.