Systemic giant-cell histiocytosis: report of a case and a review of the adult form of Letterer-Siwe disease.

The multiple classifications of histiocytic disorders, and the lack of specificity in their application, have degraded the utility of such diagnostic terms as "Letterer-Siwe Disease" and "Malignant Histiocytosis". A case is presented of a systemic histiocytic proliferation with erythrophagocytosis and giant-cell formation which does not fit into any presently accepted diagnostic niche. No similar case was found in the literature. Moreover, it appears that the entity "Adult form of Letterer-Siwe disease" has been uncritically accepted on the basis of a few poorly documented cases, and should be abandoned.