Value of demonstration of cytokeratin and leukocyte common antigen in poorly differentiated malignant tumors in fine needle aspirates

Abstract

Immunoperoxidase staining for cytokeratin and leukocyte common antigen (LCA) was applied to aspirated material from 21 well-differentiated malignant tumors ("control cases," which could be cytologically categorized) and 32 poorly differentiated malignant tumors ("study cases," whose tumor type was not clearly evident from study of the aspirate). Fifteen (48%) of the 32 poorly differentiated malignant tumors were classified as carcinomas (12 cases) or lymphomas (3 cases) by positive staining for cytokeratin or LCA, respectively. Good cytohistopathologic correlation was observed in all 7 control cases and in 11 cases of the study cases for which histologic specimens were available. The addition of staining for desmin helped in categorizing one undifferentiated tumor as a rhabdomyosarcoma. Immunostaining for vimentin was not found to be valuable in the categorization of these tumors.