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Erdheim-Chester disease is a non Langherans form of histiocytosis first described by Chester in 1930. To date, 178 cases have been reported in the literature. Age at onset is usually between 40 and 60 years, however patients of all ages can be affected. The leading clinical features are general symptoms (fever, weight loss, asthenia), bone pain, exophthalmos, diabetes insipidus and retroperitoneal damage. Bone pain affects mainly the lower limbs, particularly knees and ankles. Exophthalmos is caused by a retro-orbitar mass and is usually painless and bilateral. Diabetes insipidus may occur a few years before the other signs. Other neurological manifestations caused by infiltration of dura extending to the falx celebri or tentorium cerebelli were described. Retroperitoneal infiltrate is commonly revealed by abdominal pain or urinary signs. Pulmonary fibrosis, pleural/pericardial or skin (similar to xanthomas) involvement have been also reported, although cardiovascular involvement is often underestimated. The most specific radiological finding is bilateral and symmetric cortical osteosclerosis. The metaphyseal and diaphyseal regions of the long bones are affected. Nevertheless flat bone involvement and lytic lesions are observed. The disease is characterized histologically by a xanthogranulomatous infiltration consisting in "lipid laden" histiocytes or macrophages surrounded by fibrosis. Histiocytes are not Langherans cells and have no Birbeck granules. Immunostaining for CD1a is negative. Pathophysiology is still unknown. Mortality remains significant and is probably higher than in Langherans histiocytosis. Various treatments have been tried, sometimes improving disease course. Those include corticotherapy, chemotherapy, radiotherapy and some authors suggest interferon alpha. |