[Extramedullary hematopoyesis: compensatory mechanism or clinic syndrome? Case report and review of literature].

Extramedullary hematopoiesis (EMH) is a compensatory mechanism occurring in patients with chronic anemia. Liver, spleen, and lymph nodes are frequently involved. However, EMH may also develop in several sites such as thymus, kidneys, retroperitoneum, paravertebral areas of the thorax, lungs, bowel and others. Rarely symptomatic, it often shows a variety of clinical features. This condition, frequently, may be fatal. A correct early diagnosis of EHM might avoid, if possible, a bad prognosis. The Authors report a case where bone marrow cells were identified in centrifuge cerebrospinal fluid of a patient suffering from non-Hodgkin lymphoma.