Abstract

A case of diffuse malignant mesothelioma of peritoneum which was difficult to distinguish from metastatic anaplastic carcinoma or malignant melanoma was presented. The patient was a 50 year-old woman and complained of an abdominal pain and ascites for 20 days. Histologically, the tumor cells showed highly anaplastic appearance with sheet-like arrangement without any papillary or tubular structure. They stained Positive for cytokeratin and vimentin and negative for CEA, S-100 protein and melanoma associated antigen. A few cells within the tumor showed Positive reactivity to desmin. Ultrastructurally, the tumor cells had characteristic findings of mesothelioma such as long, exuberant, wavy microvilli with 10 to 12 of length/diameter ratio. The patient died 3 months after the diagnosis in spite of intraperitoneal chemotherapy.

• Keywords: Diffuse malignant mesothelioma;Anaplastic;Ultrastructure;Microvilli