Kenshi Sakamoto

Malignant fibrous histiocytoma induced by intra-articular injection of 9, 10-dimethyl-1, 2-benzanthracene in the rat. Pathological and enzyme histochemical studies

Malignant fibrous histiocytoma (MFH) was produced by injection of 9,10‐dimethyl‐1,2‐benzanthracene (DMBA) into the rat knee joint. The tumor was observed in or around the knee in nearly all the animals 13 to 36 weeks after the initial DMBA administration. Histologically, these lesions were of the storiform‐pleomorphic type (39/58, 67.2%), myxoid type (9/58, 15.5%), or giant cell type (8/58, 13.8%). Six cell types reported in human MFH were confirmed and phagocytosis of 0.81‐μ latex particles by histiocyte‐like cells was noted by electron microscopic examination. Acid phosphatase, β‐glucuronidase, and α‐naphthyl acetate esterase were positive in enzyme histochemical examinations. Acid phosphatase activity was electron microscopically noted primarily in the lysosomes and the Golgi apparatus of the histiocyte‐like cells. Cells from the storiform‐pleomorphic (M1) and myxoid (M2) type tumors were serially transplanted subcutaneously in the back of the rats, and are now at the thirtieth and fortieth passage, respectively. They also were studied by enzyme histochemical and electron microscopic techniques. Our observations suggested an undifferentiated mesenchymal cell origin of MFH. Transplantable MFH can be produced in rats by intra‐articular injection of DMBA, and lesions thus produced are a useful experimental model for the investigation of the histogenesis and the effect of chemotherapy of MFH. Cancer 57:2313–2322, 1986.

An unusual cause of metatarsal pain in a young kendo player

ence a gradual increase in nocturnal pain. He consulted our hospital on June 26, 1985. Physical examination revealed diffuse swelling of the outside area of the left foot and tenderness on fifth metatarsal distal portion (Fig. 1). Roentgenogram demonstrated a small oval lucent nidus surrounded by sclerotic reactive bone at the distal portion of fifth metatarsal (Fig. 2). 99mTc-bone scintigram demonstrated abnormal uptake at the area of nidus (Fig. 3). Laboratory data showed no inflammatory signs. Surgical excision of the lesion was performed on August 9, 1985, on suspicion of osteoid osteoma. A longitudinal incision was made on the distal portion of fifth metatarsal and the lesion was disclosed under radiographic control. The lesion presented a reddish appearance and minimal bulging. A en bloc excision of the lesion and bone graft were performed. Pathologic examination revealed travecular bone formation with partial calcification and proliferation of osteoblast within lacunae (Fig. 4). From these findings, osteoid osteoma was confirmed. Figure 1. Diffuse swelling is seen at the outside of the left foot.