Serial transplantable strains of nude mouse derived human malignant fibrous histiocytoma (MFH) originating in maxilla were established and the histogenesis was studied.
The tumor obtained from the recurrence of a MFH originated in the right maxilla of a 60-year-old woman. It was transplanted beneath the scapular skin in nude mice and was transferred for over 4 and a half years for 37 consecutive passages (the take rate was 220/237, 92.8%) to establish a nude mouse-transplantable MFH. In the tumors of the 15th and 34th passages, the chromosomes were analyzed and the human origin was confirmed. By light microscopic observation, polygonal histiocyte-like cells characterized by polymorphism and atypism were observed. Acid phosphatase, naphtol AS-D acetate esterase were positive by enzymatic histochemistry testing, while lysozyme, α 1-antitrypsin, and ai-antichymotrypsin were positive immunohistochemically. On electron microscopic observation, the transferred tumors were mainly composed of histiocyte-like cells. The cell membranes with filopodia, rough endoplasmic reticulum, and many lysosomes having a moderate electron density were observed in the cytoplasm, suggesting the ability of phagocytosis. Undifferentiated cells were not observed.
From these facts it appeared that the MFH would be originated from histiocytes.