[Bone scintigraphy in Erdheim-Chester disease]

Erdheim-Chester disease (ECD) is a rare disorder with fewer than 80 cases reported in the world. It consists of a non-Langerhans' cell histiocytosis that usually presents as pain due to bone involvement; however, the prognosis is marked by extraskeletal involvement. Although the final diagnosis needs an anatomophatologic study (normally through a bone biopsy), radiologic and scintigraphic findings are quasi pathognomonic. In this work, we report 2 ECD cases and their respective bone scans showing typical findings described in the literature. We found bilateral and symmetrical increased uptake of diaphyses and metaphyses of long bones, mainly in lower limbs. The mid-diaphyses and the epiphyses (partially in the first case) as well as the axial skeleton are spared.