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[967] FIGO Grade I Endometrioid Adenocarcinoma of the Uterine Corpus with Lymph Node Metastasis Closely Resembling Sinus Histiocytes: Reported Frequency in 79 Myoinvasive Cases

CM Quick, JK McKenney. University of Arkansas for Medical Sciences, Little Rock, AR

Background: Although endometrioid adenocarcinoma of the uterine corpus (EAUC) with lymph node metastasis closely mimicking sinus histiocytes has been reported in a small series, the frequency of this intranodal pattern in a consecutive series of myoinvasive tumors has not been studied previously.
Design: 139 FIGO grade I EAUC were reviewed to identify cases with myoinvasion. In myoinvasive cases, all lymph nodes sampled were reviewed to identify possible metastatic disease and the histologic pattern of each intranodal focus was recorded. Intranodal tumor cells characterized by individual discohesive cells with round nuclei, variable small nucleoli, and a rim of eosinophilic cytoplasm were scored as histiocyte-like.
Results: 79 myoinvasive FIGO grade I EAUC were identified, 72 of which had lymph node sampling (91%). 8/72 cases (11%) had lymph node metastasis in 1-3 pelvic lymph nodes; the number of sampled nodes in positive cases ranged from 8-31 (mean = 16). 5 of 8 cases (63%) with positive lymph nodes had at least some intranodal tumor with histiocyte-like morphology, a pattern that was exclusive in 3 cases (4%). The two positive lymph nodes with other admixed patterns of nodal involvement contained solid epithelial nests with marked cytoplasmic eosinophilia. All 3 cases with a pure histiocyte-like morphology were initially unrecognized.
Conclusions: In this series, 11% (8/72) of myoinvasive FIGO grade I EAUC were associated with lymph node metastasis. 5 of the 8 had at least some intranodal involvement in which the neoplastic cells closely resembled histiocytes, and in 3 cases the histiocyte-like pattern was exclusive (4%). Since lymph node metastasis with the subtle histiocyte-like morphologic pattern may be easily overlooked, increased awareness of this pattern is important to proper patient staging and treatment.
Category: Gynecologic

Monday, March 26, 2007 8:45 AM

Platform Session: Section C, Monday Morning