FINE-NEEDLE ASPIRATION CYTOLOGIC DIAGNOSIS OF LYMPHOEPITHELIOMA-LIKE CARCINOMA OF THE LUNG - REPORT OF 2 CASES WITH IMMUNOHISTOCHEMICAL STUDY

Lymphoepithelioma is a term used to describe an undifferentiated carci noma with prominent lymphoid infiltration in the nasopharynx, Recently , tumors with similar histology, designated as lymphoepithelioma-like carcinomas, have been described in other sites including the lung, The authors report two cases of pulmonary lymphoepithelioma-like carcinom a that were correctly diagnosed by fine-needle aspiration cytology, Th e distinctive cytologic features consist of cohesive sheets and cluste rs of spindle tumor cells, which possess moderately pleomorphic vesicu lar nuclei and prominent nucleoli that are intimately intermixed with numerous small lymphocytes, Immunohistochemical study, performed on th e cell block preparation, revealed strong positive staining of these t umor cells for epithelial markers. In both cases, the cytologic diagno ses were confirmed subsequently by histologic examination of the resec ted surgical specimens. Cytologically, the differential diagnoses incl ude granulomatous inflammatory diseases (especially tuberculosis), mal ignant lymphoma, melanoma, and metastatic sarcoma. The characteristic cytology of the tumor cells, together with their pattern of immunohist ochemical staining, are helpful to distinguish lmyphoepithelioma-like carcinoma from the differential diagnoses. In these cases, careful exa mination of the nasopharynx, preferably with multiple random mucosal b iopsies, is essential for the exclusion of nasopharyngeal undifferenti ated carcinoma because of the obvious differences in treatment and pro gnosis.