HYPERPLASTIC MESOTHELIAL CELLS WITHIN ABDOMINAL LYMPH-NODES - MIMIC OF METASTATIC OVARIAN-CARCINOMA AND SEROUS BORDERLINE TUMOR - A REPORT OF 2 CASES ASSOCIATED WITH OVARIAN NEOPLASMS

Two cases of hyperplastic mesothelial cells within intra-abdominal lym ph nodes were encountered in staging procedures in a 59-year-old woman with bilateral ovarian serous borderline tumors and in a 21-year-old woman with a Sertoli-Leydig cell tumor of intermediate differentiation . Both patients also had mesothelial hyperplasia of the pelvic and abd ominal peritoneum; in one of them, the hyperplasia was striking, The i ntranodal mesothelial cells occupied the sinusoids of the lymph nodes and were initially suspected of being metastatic from the ovarian tumo r in each case, The appearance of the cells on routine stains suggeste d the correct diagnosis, which was confirmed by histochemical and immu nohistochemical staining, These cases represent the first reported exa mples of mesothelial cells within abdominal lymph nodes, although simi lar involvement of mediastinal lymph nodes has been described in three patients with pleural effusions. Intranodal mesothelial cells should be distinguished from metastatic tumor, an error that could result in inaccurate staging in a patient with a known tumor or prompt a futile search for an occult primary tumor, Moreover, it is important that in studies evaluating the frequency of nodal involvement by serous border line tumors, intranodal mesothelial cells should not be misinterpreted as metastatic borderline tumor, a distinction that can be difficult w ith only routinely stained sections.