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.

Differential central distribution of optic nerve components in the rat.

The distribution of Fink-Heimer positive degeneration and neurofibrillar proliferation has been examined in the dorsal lateral geniculate nucleus (dLGN) and superior colliculus of albino and pigmented rats following enucleation between post-natal days 12 and 30 and as adults. With survival times of 6 h to 5 days following enucleation, the location of maximum degenerative reaction stained by the Fink-Heimer method changes with increasing survival time in both regions. In the dLGN contralateral to the eye removal the earliest degeneration appears in a lamina occupying the medioventral extent of the nucleus and is rapidly removed; later degeneration fills a central lamina of the nucleus with a patch of degeneration extending to the outer surface of the nucleus at the mediodorsal margin. The latest occurring degeneration fills the outermost lamina and is still obvious when degeneration is largely dispersed from the inner and central laminae; this outer lamina shows an early filamentous degenerative reaction in the adult. The uncrossed optic pathway occupies a portion of the central lamina of the nucleus, and in albino animals it shows a rapid degeneration and dispersion similar to the innermost lamina on the crossed side; in the pigmented animals degeneration of the uncrossed projection starts as early as that of the albino but persists as long as the degeneration of the central lamina on the crossed side. The degeneration time of the sprouted, uncrossed pathway resulting from unilateral enucleation at birth is similar in albino and pigmented rats and resembles in timing the normal uncrossed pathway of pigmented rats. These results suggest that there are at least 3 different fiber populations in the rat optic nerve with different distribution in the dLGN. The uncrossed optic pathway of albino and pigmented rats appears to differ in fiber composition; this may relate to aberrations in mapping of uncrossed projections in the albino.