I. Peter Shintaku

Immunoreactive neuron-specific enolase, bombesin, and chromogranin as markers for neuroendocrine lung tumors

Sixty-four lung tumors were evaluated for the presence of immunoreactive neuron-specific enolase (NSE), bombesin (Bn), and chromogranin (Cg) to assess their value as markers for neuroendocrine cells in the histologic diagnosis of pulmonary neoplasms. Staining was correlated with the presence and density of neurosecretory granules (number of neurosecretory granules per unit cytoplasmic cross-sectional area) as determined by planimetry on electron micrographs. The cytoplasmic density of neurosecretory granules was significantly greater in the carcinoid tumors than in the small cell carcinomas (P less than 0.001). Neuron-specific enolase was localized in all of the neuroendocrine granule-bearing tumors but was also present in 57 per cent of the nonneuroendocrine carcinomas. Bombesin was present in 68 per cent of the neuroendocrine tumors and in less than 1 per cent of the nonneuroendocrine tumors. Staining for Cg appeared to correlate with the density of neuroendocrine granules, with staining in carcinoid tumors but no staining in small cell anaplastic carcinomas. A panel of antibodies may be required for the reliable identification of neuroendocrine lung tumors by immunohistochemical techniques.

Localized fibrous mesothelioma: An immunohistochemical and electron microscopic study

The absence of keratin staining in tumor cells from localized fibrous mesotheliomas in both paraffin-embedded and frozen sections with sensitive peroxidase-antiperoxidase and avidin-biotin techniques is described. In addition ot the absence of staining for whole-stratum corneum keratin proteins, sections were negative for keratins of different molecular weights (45, 55, and 63 kilodaltons) that are characteristically present in mesothelial cells. Ultrastructurally, the cells most closely resembled mesenchymal cells of the fibroblastic type. These findings are in accordance with recent theories that relate the derivation of localized fibrous mesotheliomas to nonmesothelial cells, including subpleural connective tissue. Based on differences in immunohistochemical staining, the tumors appear to be unrelated to diffuse malignant mesotheliomas.

Distribution of T-cell phenotypic subsets and surface immunoglobulin-bearing lymphocytes in lymph nodes from male homosexuals with persistent generalized adenopathy: An immunohistochemical and ultrastructural study

Lymph nodes from homosexual men with persistent generalized adenopathy were evaluated for distribution of T-cell phenotypic subsets and surface immunoglobulin(SIg)-bearing lymphocytes. Electron microscopy revealed tubulovesicular structures within lymphocytes but no multivesicular rosettes. Eight to 33 per cent of the lymphocytes within germinal centers were suppressor T cells, compared with germinal centers from control lymph nodes, in which these cells were rare (P = 0.002). Significantly greater percentage of suppressor/cytotoxic T lymphocytes were also present in the paracortex and follicular mantles of lymph nodes from the homosexual group (P = 0.002 and 0.007, respectively). Percentages of helper T lymphocytes were significantly decreased in germinal centers (P = 0.008) and paracortical regions (P = 0.002). Florid follicular hyperplasia with aberrations in follicular architecture was the most common histologic pattern, but one node with diffuse hyperplasia and subtotal effacement of architecture revealed depletion of SIg-bearing lymphocytes and increased numbers of suppressor T cells. Reversed helper-to-suppressor T-cell ratios in lymph nodes from homosexuals with generalized adenopathy may be related to viral infection and contribute to immune deficiency in this group.

Epithelial membrane antigen in the cytodiagnosis of effusions and aspirates: Immunocytochemical and ultrastructural localization in benign and malignant cells

Immunoreactivity for epithelial membrane antigen (EMA) was evaluated in exfoliated benign and malignant cells using immunoperoxidase and immunogold techniques. In addition, protein A‐colloidal gold was used for ultrastructural localization of EMA. Our results suggest that EMA is useful in distinguishing adenocarcinoma cells (strongly positive) from reactive mesothelial cells (negative or weakly positive), lymphoid cells (negative), and a variety of nonepithelial neoplasms (negative) with which they may be confused. Exfoliated cells from two mesotheliomas were also strongly positive for EMA. Ultrastructurally, EMA was distributed in a dense, even, linear pattern along the cell membrane and microvillous surface processes of adenocarcinoma cells. A similar but sparse distribution pattern was observed in reactive mesothelial cells. These observations reflect the increased sensitivity and higher resolution of the immunogold technique. Diagn Cytopathol 1987;3:41–49.

Peripheral T cell lymphoma (immunoblastic sarcoma of T cell type): An immuno-ultrastructural study

Use of monoclonal antibodies directed against T cell antigens for the phenotypic characterization of neoplastic lymphoid cells in peripheral T cell lymphomas is described. Studies of cryostat sections revealed the distribution of T cell subsets in nodal and extranodal infiltrates, and immuno-ultrastructural techniques demonstrated discrete localization of T cell antigens to the cytoplasmic membranes of neoplastic cells. Although histologically similar, the tumors appeared heterogeneous as to their immunologic phenotype, with the majority demonstrating markers for T helper/inducer lymphocytes.