UNDIFFERENTIATED TUMORS - AN IMMUNOHISTOCHEMICAL ANALYSIS ON BIOPSIES

Immunohistochemical staining was performed on 145 biopsies with a diag nosis of undifferentiated or poorly differentiated tumor in order to c lassify them into lymphoid, epithelial, or mesenchymal in origin. It w as possible to arrive at a histogenetic diagnosis on immunostaining in 85.5% of cases. Immunostaining confirmed the diagnosis in 32.4% and c ontributed to diagnosis in 53.1%. Malignant lymphoma was the most comm on diagnosis (35.9%), followed by carcinoma (23.4%). A panel of antibo dies consisting of anti-common leucocyte antigen (LCA), anti-epithelia l membrane antigen (EMA), anti-cytokeratin (CK), anti-low to intermedi ate molecular weight cytokeratin (CAM 5.2), anti-S-100 protein (S-100) , and anti-vimentin (VM) may resolve, to a large extent, some of the c ommon diagnostic problems. (C) 1994 Wiley-Liss, Inc.