Cutaneous neuroendocrine (Merkel cell) carcinoma: an immunophenotypic, clinicopathologic, and flow cytometric study.

Twenty-one cases of cutaneous neuroendocrine (Merkel cell) carcinoma (CNEC) were examined by the ABC-immunoperoxidase method with a panel of antibodies to 5 intermediate filaments, 6 neuroendocrine-associated antigens, 6 peptide hormones, as well as melanoma-associated cytoplasmic antigen (HMB-45) and leukocyte common antigen. All tumors showed strong cytokeratin staining in characteristic dense, inclusion-like, cytoplasmic globules and in a reticular peripheral cytoplasmic pattern. Cytoplasmic coexpression of inclusions of neurofilament antigen was observed in 9/21 cases. Staining for one or more neuroendocrine markers in formalin-fixed tissue (bombesin, 7/20; chromogranin, 11/21; synaptophysin, 6/21) was weak and focal but present in 17/21 cases. In 3 cases, sections of unfixed, snap-frozen tumor were compared with formalin-fixed tissue, and these showed strong, diffuse staining for multiple neuroendocrine antigens. Immunostaining for peptide hormones was not observed, with the exception of weak, focal staining for insulin (1 case), calcitonin (1 case) and somatostatin (2 cases). In 13 cases DNA indices and S-phase fractions (SPF) were determined by flow cytometry on nuclear suspensions from paraffin blocks. DNA histograms in 12 of 13 cases had normal range DNA content (diploid) and elevated S-phase fractions (mean 15%, range 8 to 22%). Mean SPF was not significantly different in the group of patients who developed recurrent and/or metastatic disease (15.6%, N = 10) compared with patients without recurrence (15.8%, N = 10).(ABSTRACT TRUNCATED AT 250 WORDS)

Immunological studies on the occurrence and properties of chromogranin A and B and secretogranin II in endocrine tumors.

We investigated a variety of endocrine tumors for the presence of chromogranins A and B and secretogranin II. These antigens were identified by one- and two-dimensional immunoblotting and in some cases by immunohistochemistry. An antigen corresponding in electrophoretic behavior to adrenal chromogranin A was present in all types of tumors, including insulinomas, oat cell carcinomas, and Merkel cell tumors of the skin. Chromogranin B had a much more limited distribution. This antigen could not be detected in parathyroid adenomas, oat cell carcinomas, or Merkel cell tumors, either by immunoblotting and immunohistochemistry. The occurrence of secretogranin II was similar to that of chromogranin B, with the exception of a positive reaction in Merkel cell tumors. In benign pheochromocytomas, all three antigens were found consistently; whereas in two of three malignant pheochromocytomas, chromogranin B was absent. Our study establishes that in most cases chromogranins and secretogranin in tumors are identical to the adrenal antigens, but that these antigens are not always stored together. Chromogranin A is the most widely distributed marker for endocrine tumors.

Neuroendocrine carcinoma of the skin (Merkel cell carcinoma): immunocytochemical study of a case.

The immunocytochemical phenotype was evaluated in a case of Merkel cell carcinoma of the skin. Intermediate filaments, i.e. neurofilament, glial fibrillary acid protein, cytokeratins, keratin and panfilament as well as S-100 protein, calcitonin and epithelial membrane antigen were detected by immunoperoxidase methods. Nodular positivity for neurofilament was observed. The remaining intermediate filaments and other markers were negative. Thus the origin of Merkel cell carcinoma appears uncertain and this tumor probably has neuroendocrine activity.

[Lectin staining of a Merkel cell tumor]. / Marcaje mediante lectinas de un tumor de células de Merkel.

The authors studied a Merkel's cell tumor with lectins. There is pattern of normal epidermis, but we see the N-acetyl-glucosamine an oligosaccharide not present in epidermis.