[Epithelioid sarcoma--immunohistochemical and ultrastructural study]

Five cases of epithelioid sarcoma are reported, of which four were studied by immunohistochemistry and one by electron microscopy. Immunohistochemically, the results of cytokeratin showed that these four cases were positive to different degrees by polyclonal cytokeratin and three out of four revealed positive results with low molecular weight cytokeratin monoclonal antibody. Two cases were positive with carcinoembryonic antigen and the other two were negative. The immunohistochemical stain was helpful for differential diagnosis from other sarcomas, such as malignant fibrous histiocytoma and rhabdomyosarcoma. By electron microscopy, tumor cells could be divided into light and dark cells which possessed more or less cell organelles, intermediate microfilaments in the cytoplasm and numerous pinocytic vesicles lying along the cell membrane. The occasional presence of poorly developed desmosomes or the absence of tonofibril bundles and glandular structures can rule out the diagnosis of carcinoma. One of these cases was originally diagnosed as metastatic carcinoma to the skin by light microscopy, which was refuted by electron microscopy, and the keratin positive reaction by immunohistochemistry was helpful for the diagnosis of epithelioid sarcoma. Therefore, the authors suggest that immunohistochemical and electron microscopic studies be used for diagnosing difficult cases of epithelioid sarcoma. From our observation, we consider that the cells of epithelioid sarcoma may derive from undifferentiated mesenchymal cells possessing the potentials of differentiating into synovioblasts, histiocytes or fibroblasts.

[Renal angiomyolipoma--a clinicopathologic study of 16 cases]

A clinicopathologic study on 16 cases of renal angiomyolipoma is presented. Eleven were women and 5 men. The age ranged from 23 to 80 years with an average of 44.4. The course was from three days to one year. Abdominal mass, pain and hematuria were the main symptoms. Some individual cases were associated with tuberous sclerosis. Spontaneous rupture of the kidney was the principal complication often resulting in shock. The tumor was amenable to resection with a cure rate of 100% without recurrence, metastasis or infiltration of the large renal veins. The prognosis was good. B-type ultrasound and CT scan were helpful in the clinical diagnosis. Of 16 cases, 15 tumors occurred in unilateral kidney, in which the mass was usually located in one pole of the organ. The other tumor involved bilateral kidneys. The tumor was easily misdiagnosed as renal carcinoma by gross examination because of its being relatively large, yellow on the cut surface with hemorrhage and necrosis and often infiltrating tissues surrounding the kidney. Histologically, the tumor consisted of mature blood vessels, smooth muscles and adipose tissues. Sometimes, misdiagnosis of the renal angiomyolipoma with malignant change or angiomyoliposarcoma was made because of the active growth of the smooth muscle and adipose cells. In this paper, special emphasis is put in the discussion of the pathologic features and and causes leading to the misdiagnosis. Basing on long-term follow-up, it is suggested that angiomyolipoma of the kidney be a benign tumor of the hamartomatous nature.