Fine-Needle Aspiration Cytology with Immunocytochemistry of Extranodal Manifestations of Non-Hodgkin's Lymphoma.

Sixty-three patients with extranodal manifestations of non-Hodgkin's lymphoma were examined with fine-needle aspiration cytology and diagnosed according to the Kiel classification. Cytospin preparations were made from the aspirates and used for immunocytochemical analysis. Primary extranodal manifestations were found in 25 cases, while 16 patients had primary extranodal and nodal disease. Twenty-two patients experienced extranodal relapse of lymphoma originally limited to lymph nodes (16) or extranodal sites (6). Cytologic high-grade lymphomas were diagnosed in 17 (68%) of the primary extranodal lymphomas, 14 (64%) of those with extranodal relapse and 11 (69 %) of those with extranodal and nodal disease. Three cases were diagnosed as histiocytic lymphomas. None of the lymphoma subgroups had any preponderance for specific extranodal sites. Forty patients had a histologic examination and in 34 of these cases the cytologic and histologic diagnoses were in agreement. There were four cases with divergent histologic and cytologic diagnoses. Two patients were diagnosed as Hodgkin's disease on sections while smears from the extranodal recurrences showed an unequivocal picture of high-grade non-Hodgkin's lymphoma. Two smears showed an immunocytoma and a lymphoblastic lymphoma, respectively, while histology was inconclusive. In two patients with histologic diagnosis of centroblastic/centrocytic lymphoma, aspiration cytology at relapse (> 1 year later) revealed centroblastic lymphoma in both cases. Immunocytochemistry identified 57 B-cell, 3 T-cell and 3 true histiocytic lymphomas. A monoclonal light chain expression was present in 50 (88 %) of the B-cell lymphomas. Immunohistochemical evaluation of light chain expression was performed in 21 cases and the results were in agreement with the immunocytochemical analysis. Our results show that fine-needle aspiration cytology aided by immunocytochemistry offers a method with a very high accuracy for the diagnosis and classification of extranodal manifestations of non-Hodgkin's lymphoma.