[Histiocytic cytophagic panniculitis].

UNLABELLED A HISTOPATHOLOGICAL DIAGNOSIS: Histiocytic cytophagic panniculitis is the specific skin finding in the reactive hemophagocytic syndrome. It is a feverish nodular eruption which accompanies the other clinical and biological features of the reactive hemophagocytic syndrome. Histopathologic changes are diagnostic and consist in a lobular panniculitis characterized by the presence of a histiocytic infiltration of the fat. Histiocytes are benign in appearance and show variable degree of phagocytosis. INFECTION AND IMMUNE ANOMALIES In more than 50% of the cases, the disease is triggered by an infection (mainly a viral infection from the herpes-virus family) in a patient with altered immune function (immunodeficiency, autoimmune disease, hematological disease). Search for subcutaneous T-cell lymphoma is mandatory, but is a diagnostic challenge. Such lymphomas are associated with histologic features of histiocytic cytophagic panniculitis. PATHOPHYSIOLOGY Histiocytes in the histiocytic cytophagic panniculitis are activated by an abnormal cytokine secretion (interferon gamma, granulocyte/macrophage colony stimulating factor, phagocytosis inducing factor, ...) from neoplastic or reactive T cells. CLINICAL TRIALS Untreated, the course of the disease is usually lethal. Etiologic treatment should be provided whenever possible. Symptomatic treatment consists in transfusion and corticosteroid therapy. Etoposide, and sometimes cyclosporin, have been reported to be efficient. Some authors recommend that histiocytic cytophagic panniculitis should always be treated with a CHOP-like polychemotherapy. More recently, good results were obtained with high dose intravenous immunoglobulin and this treatment therefore deserves further evaluation.