HYPERPLASTIC MESOTHELIAL CELLS IN LYMPH-NODES - REPORT OF 6 CASES OF A BENIGN PROCESS THAT CAN SIMULATE METASTATIC INVOLVEMENT BY MESOTHELIOMA OR CARCINOMA

We report six cases of hyperplastic mesothelial cells located in the s inuses of lymph nodes. All patients but one had a concurrent serosal f luid collection (two pericardial, two pleural, one abdominal) at the t ime of the lymph node biopsy. All effusions cleared with treatment of the underlying disorder, which included lymphoproliferative processes, congestive heart failure, and inflammatory diseases (Dressler syndrom e, vasculitis, and glomerulonephritis). Four cases were associated wit h vascular prominence of the involved nodal sinuses, a feature that ma y reflect the cause of the underlying effusion or support the transien t persistence of benign mesothelial cells in lymph nodes. Two cases we re characterized by distention of the nodal sinuses by sheets of mitot ically active mesothelial cells. The differential diagnosis includes m etastatic carcinoma, keratin-positive dendritic cells native to lymph nodes, and metastatic malignant mesothelioma. Because the latter share s both clinical and morphological features with cases of benign mesoth elial cells in lymph nodes, we believe that this distinction may not a lways be possible in a given biopsy specimen and therefore that carefu l clinical follow-up is required in such cases. Copyright (C) 1998 by W.B. Saunders Company.