Erdheim-Chester disease (ECD) is a non-Langerhans cell systemic histiocytosis with an unknown etiology and pathogenesis. In this illness there is generalized sclerosis of the long bones that does not involve the epiphysis and axial skeleton. The extraskeletal sites may also be involved such as the retroperitoneal space, lungs, kidneys, brain, retro-orbital space, and heart .Here we report a case of 45 year old who presented with a chief complaint of back pain for 6 months duration. It was gradually increasing in intensity. On physical examination there was tenderness on palpation of the spinous process of thoracic vertebrae. He was diagnosed as Erdheim-Chester disease (ECD) on the basis of clinical , radiological and histopathological features followed by immunohistochemistry confirmation. Histologically, it shows diffuse inflammatory infiltrate comprising of lymphocytic aggregates with large foamy histiocytes, few Touton-like giant cells along with fibrosis. The histiocytes show positivity for CD68 and negativity for CD1a, S100 protein, langerin which differentiates it from Langerhans cell histiocytosis. Currently there is no effective therapy for this illness.

Keywords: Non-Langerhans cell systemic histiocytosis , Foamy histiocytes.

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Verma Anil Kumar

Senior Resident, Department of transfusion medicine & blood bank, All India Institute of Medical Sciences, Raipur