ONE OF the most interesting recent developments in the field of pathology is the concept, first advanced by Farber and Green,1 that "eosinophilic granuloma of bone" is the mildest form of a group of reticuloendothelial diseases. Other members of this group of "peculiar inflammatory histiocytosis" (Jaffe and Lichtenstein2) are Hand-Schüller-Christian and Letterer-Siwe diseases. If this concept is correct, it was to be expected that cases of eosinophilic granuloma would be observed in which other organs besides the bones are affected.
The first case of this kind was published by Curtis and Cawley.3 Their patient was a 2 year old girl who had cutaneous manifestations of specific character, in addition to multiple involvement of bones. The case which forms the basis of our report was seen at the Marshfield Clinic in January 1946 and was diagnosed clinically as Schüller-Christian disease. Tissue sections of the bone lesion, however, were