Immunohistochemical study of malignant melanoma

Formalin fixed paraffin embedded sections of 15 cases of malignant melanoma of the skin were studied immunohistochemically for the presence of vimentin, cytokeratin and neurofilament proteins. The original diagnosis of malignant melanoma was confirmed in each case based on a histologic examination. It was found that vimentin was present in the cytoplasm of the majority of all cases. However, cytokeratin immunostaining was found in three out of 15 melanoma cases. In contrast, two melanoma cases contained neurofilament positive tumor cells. It was concluded that melanomas containing exclusively vimentin intermediate filaments prove to be useful in the differential diagnosis of melanomas from other tumor types. Also, melanoma cells are considered as interconverted cells as they display both mesenchymal and epithelial phenotypes

Correlative histopathological and immunohistochemical study of small in cell carcinoma, large cell carcinoma and adenocarcinoma of the lung biopsy and cytology specimens

Thirty cases of lung carcinoma specimens, collected by open biopsy [9 cases], bronchoscopic biopsy [21 cases], in additional to five cases of broncheal brush cytology and 15 cases of plural fluid aspiration cytology were examined histopathologically, cytologically and immunohistochemically. Differentiation between small and large cell carcinoma by light microscopic examination was more or less difficult especially with small biopsy specimens. Meanwhile, small cells with large amount of cytoplasm were distinguished from large cells by the assessment of the nucleus, cytoplasm, nuclear cytoplasmic ratio, cell arrangmement and the positivity of large cells to cytokeratin. Criteria for diagnosing adenocarcinoma were cell arrangement and mucin positivity by mucicarmin stain. Occasional cases show cytokeratin positive granules