Pseudomesotheliomatous carcinoma involving pleura and peritoneum: A clinicopathologic and immunohistochemical study of three cases.

Pseudomesotheliomatous carcinoma is a rare variant of peripheral adenocarcinoma of the lung that can manifest clinical, radiologic, and pathologic features similar to malignant mesothelioma. We present three patients with pseudomesotheliomatous carcinoma of the lung. In one patient the carcinoma extended beyond the thorax and extensively involved the peritoneum, mesentery, omentum, and intestines. All patients experienced weight loss and chest pain. All were white men aged 63, 65, and 67 years. Two were smokers and had shortness of breath, cough, and pleural effusion. One had a history of asbestos exposure. No patient developed dyspnea or hemoptysis. One was successfully treated for prostatic carcinoma 18 months earlier. Radiographically, all tumors were pleura-based. Grossly, the tumors spread extensively over pleural (and in one case peritoneal) surfaces and mimicked malignant mesothelioma. Histologically, all tumors were poorly differentiated and necrotic; two tumors exhibited spindle-cell components and desmoplasia. Mucin production was detectable in none, 10%, and 50% of tumor cells. The percentages of tumor cells immunoreactive for Ber-EP4 were 70%, 100%, and 80%; for Leu MI 0%, 90%, and 50%; for epithelial membrane antigen 80%, 80%, and 100%; for B 72.3%, 0%, 90%, and 20%; for polyclonal carcinoembryonic antigen 0%, 10%, and 10%; and for monoclonal 5%, 0%, and 0%. Of these, Ber-EP4 and B 72.3 rendered the most reliable diagnostic results. The clinical, radiologic, and gross and routine histologic findings were similar to those of a malignant mesothelioma; the final diagnosis could be made based mainly on immunocytochemical results. We have reviewed the English and German literature regarding 65 such tumors and present our experience with three additional cases. We emphasize the application of immunocytochemical studies on pleura-based poorly or undifferentiated malignant tumors of unknown origin.

Papillary serous carcinoma of the peritoneum in a man: a case report.

BACKGROUND: Papillary serous carcinoma of the peritoneum (PSCP) is a rare primary peritoneal tumor, described exclusively in women. It is believed to arise from the secondary müllerian system, which is comprised of the pelvic and lower abdominal mesothelial lining and subjacent (subcoelomic) mesenchyme in women. Both mesotheliomas and PSCP arise from the coelomic epithelium, but are clinicopathologically and biologically distinct entities. METHODS: The authors report clinicopathologic findings in a man, age 74 years, who died 3 months after the diagnosis of an extensive malignant abdominal disease. RESULTS: The routine histologic and immunocytochemical studies of tumor tissue, obtained during the patient's lifetime and at autopsy, validated the unique occurrence of PSCP in a man. CONCLUSIONS: This case illustrates that PSCP can occur in a man and that this diagnosis may be considered in the differential diagnosis of papillary serous tumors of the peritoneum in male patients. Although rare, PSCP is a diagnostically distinct entity the treatment of which is similar to ovarian serous tumors rather than mesotheliomas.

Comparative immunoreactivity of CD-68 and HMB-45 in malignant melanoma, neural tumors and nevi.

The monoclonal antibody CD 68 (KP 1) reacts with fibrohistiocytic and some epithelial neoplasms; its reactivity compared with that of HMB 45 in malignant melanoma (MM) and neural tumors needs further elucidation. Using a streptavidin-biotin-immunoperoxidase procedure, we examined the reactivity of 65 MM (46 conventional, 1 polypoid, 6 desmoplastic [DMM], and 12 metastatic), 21 neurofibromas, 1 neurofibrosarcoma, 10 schwannomas, 1 perineurioma, 2 neurothekeomas, and 14 blue and 26 other nevi for CD-68, HMB-45-defined antigen, S 100 and neurofilament protein. A positive staining for CD 68 was observed in 38 of 42 primary, 5 of 6 DMM, and 11 of 12 metastatic melanomas; 6 of 10 schwannomas; 5 of 10 nevi with junctional component and all 14 blue nevi. All 21 neurofibromas, 1 each neurofibrosarcoma and perineurioma, both neurothekeomas, and all 12 nevi with dermal component were CD 68-negative. HBM 45 was expressed by all 44 primary, none of 6 DMM, and 7 of 12 metastatic melanomas; by none of 10 schwannomas, 6 neurofibromas, 1 neurofibrosarcoma, 1 perineurioma and 2 neurothekeomas. Both junctional nevi, 8 of 10 nevi with junctional components, 1 of 10 dermal components of junctional nevi, and 11 of 13 blue nevi were also HMB 45 positive. Except for 1 perineurioma, S 100 decorated all tumors examined. NF was immunoreactive in 1 of 45 conventional melanomas, 2 of 21 neurofibromas, 2 of 10 schwannomas, and 3 of 10 blue nevi; it was non-reactive in all polypoid, desmoplastic and metastatic melanomas; neurofibrosarcoma, perineurioma, neurothekeoma and other nevi. We conclude that the CD-68-reactivity in primary melanomas, neurofibromas, neurofibrosarcomas, perineuriomas, and nevi was similar to that of HMB 45. The significantly higher CD 68-positivity than of HMB 45 in metastatic and desmoplastic melanomas and schwannomas may be of diagnostic value.