Mucin-positive epithelial mesotheliomas: a histochemical, immunohistochemical, and ultrastructural comparison with mucin-producing pulmonary adenocarcinomas.

Pathologists routinely use histochemistry, immunohistochemistry, and electron microscopy to differentiate epithelial mesotheliomas from pulmonary adenocarcinomas. Epithelial mesotheliomas are usually mucicarmine-, PAS-diastase, and carcinoembryonic antigen-negative, whereas about 60-75% of pulmonary adenocarcinomas are mucicarmine- and PAS-diastase-positive, and about 90% express polyclonal carcinoembryonic antigen. During a pathologic evaluation of pleural neoplasms between 1975 and 1990, 10 epithelial mesotheliomas were identified that were mucicarmine- and in some instances PAS-diastase-positive (diagnosis of mesothelioma confirmed by ultrastructural examination), with four mesotheliomas focally expressing carcinoembryonic antigen. The mucicarmine, PAS-diastase, and carcinoembryonic antigen staining were usually eradicated or reduced in intensity by pretreatment of the tissue sections with hyaluronidase, suggesting that hyaluronic acid was responsible for the positive mucin reactions. In three cases the epithelial mesotheliomas showed focal regions of mucicarmine, PAS-d-, and Alcian blue-hyaluronidase-resistant staining. In contrast, 10 mucicarmine-, PAS-diastase-, Alcian blue-, and carcinoembryonic antigen-positive pulmonary adenocarcinomas were not affected by hyaluronidase pretreatment of the tissue. Besides the usual ultrastructural features of well- to moderately well-differentiated epithelial mesotheliomas, the mucin-positive epithelial mesotheliomas often showed medium-electron-dense secretory material covering the microvilli, aggregates of medium electron-dense material in association with the microvilli, producing an ultrastructural morphology that has been observed only in epithelial mesotheliomas.

Amphicrine carcinoma of the uterine cervix.

A case of amphicrine carcinoma of the uterine cervix is described in a 27-year-old woman whose initial cervical biopsy specimen showed small cell undifferentiated neuroendocrine carcinoma. Despite an initial complete clinical response to VP-16 and carboplatin, residual tumor was noted in the cervical cone biopsy specimen and she was treated with external-beam irradiation and cesium implants. The neoplasm subsequently metastasized and required additional VP-16 and carboplatin for control. The pathologic features and biologic behavior of this unusual type of neuroendocrine neoplasm are described in this case report.

Induction of tubuloreticular structures in cultured human endothelial cells by recombinant interferon alfa and beta.

Tubuloreticular structures were induced in human umbilical vein endothelial cells cultured in media containing recombinant interferon alfa and beta but not in media containing recombinant interferon gamma or other agents that induce interferon, such as 5-bromodeoxyuridine or polyinosinicpolycytidylic acid. Recombinant interferon beta induced tubuloreticular structures in endothelial cells at a lower concentration and in a greater percentage of cell sections than recombinant interferon alfa. This report of tubuloreticular structures being induced in vitro in nonlymphoid cells provides evidence that interferon is the substance that causes the formation of tubuloreticular structures in endothelial cells in vivo.

Interdigitating reticulum cell sarcoma with unusual features.

A case of interdigitating reticulum cell sarcoma is reported in a cervical lymph node of a 67-year-old man who had a previously diagnosed nodular lymphocytic lymphoma in the same anatomic location. Ultrastructurally, the neoplastic cells contained cylindrical confronting cisternae, and associated benign lymphocytes had tubuloreticular structures in their cytoplasm. The patient was treated with combination chemotherapy-radiation therapy and is alive and well with no evidence of disease approximately 2 years after completing therapy. The clinical and pathologic features of previously reported cases of interdigitating reticulum cell sarcomas are compared to those of the reported case.