[Midline malignant histiocytosis--diagnostic and prognostic study of 42 patients]

42 patients of midline malignant histiocytosis are reported. The differential diagnosis should be made carefully, for its clinical sign and pathologic picture are similar to some neoplasms, inflammatory or allergic diseases. The 3, 5 and 10 year survival rates are 52.4%, 38.1% and 21.4% respectively. The survival rate of those in the prodromal stage is the highest. The authors suggest that this disease probably belongs to the malignant tumor of mononuclear macrophage system and be a special type of malignant histiocytosis. It may be designated as the midline malignant histiocytosis.