Benign lymph node inclusions are commonly encountered during surgery f
or gynecologic neoplasms and are potential mimics of metastatic diseas
e. A 52-year-old woman presented with ascites, a complex adnexal mass,
and a CA-125 of 1891 units/mL. A staging laparotomy was performed, di
agnosing struma ovarii. Pathologic evaluation of pelvic lymph nodes de
monstrated mesothelial inclusions in nodal sinuses suspicious for meta
static disease. Immunocytochemical evaluation revealed benign mesothel
ial inclusions rather than metastatic thyroid carcinoma. Benign mesoth
elial lymph node inclusions in nodal sinuses are potential mimics of m
etastatic carcinoma. Their presence in pelvic lymph nodes has not prev
iously been reported. Given the potential difficulty in determining th
e origin of these inclusions, immunocytochemical evaluation is useful
in reaching the correct diagnosis. (C) 1998 Academic Press.