[1099] An Analysis of Histologic Features Associated with Occult Lymph Node Metastasis in Clinical Stage I FIGO Grade I Endometrial Carcinoma

G Han, MM Leitao, Jr, N Abu-Rustum, RA Soslow. Memorial Sloan-Kettering Cancer Center, New York

Background: A previous study of microcystic, elongated and fragmented (MELF) invasion in endometrial endometrioid adenocarcinoma (EEC), including all FIGO grades and stages, failed to find associations with clinical outcome. We studied histologic features associated with occult lymph node (LN) metastasis in FIGO grade 1, clinical FIGO stage I EEC with occult LN metastasis.
Design: Clinical stage I FIGO grade 1 myoinvasive EEC with occult positive LN(s) (n=18) were identified in a clinical database. Deep myometrial invasion (DMI >50%), stromal reaction, lymphovascular invasion (LVI) (absent, mild - 1 focus, severe - diffuse or multifocal), metaplasia type, and adenomyosis (absent, mild - 1-3 foci, severe - 4 or more foci) were assessed. Controls were 36 node-negative, myoinvasive, EECs matched for grade, patient age, body mass index and surgery date. The number, size (isolated tumor cells (ITC) <0.2 mm, micrometastasis 0.2-2 mm, macrometastasis >2 mm) and histology of LN metastases were evaluated.
Results: LN-positive cases had significantly higher rates of LVI (p<0.001) and MELF invasion (p=0.03) than LN-negative cases on univariate analysis (Table 1). LVI was the only independently associated factor for LN metastasis (odds ratio 32.49, p=0.002) on multivariate analysis. Macrometastases were seen in only 7 cases (39%), with or without micrometastasis and/or ITC. ITCs were seen in 12 cases (67%), with 8 cases containing ITC only (44%). In 3 cases (17%), sentinel LN workup was required to detect ITCs or micrometastases. Histiocyte-like tumor cells in LNs were seen in 11 cases (61%). ITCs and micrometastases often failed to resemble the primary tumor.

Table 1. Summary of Histologic Features

	DMI	MELF	LVI	Mucinous Metaplasia	Myxoid Stroma	Adenomyosis
Node-positive (n=18)	7 (39%)	12 (67%)	A 2 (11%), M 3 (17%), S 13 (72%)	4 (22%)	12 (67%)	A 10 (56%), M 3 (17%), S 5 (28%)
Node-negative (n=36)	9 (25%)	13 (36%)	A 26 (72%), M 4 (11%), S 6 (17%)	9 (25%)	15 (42%)	A 20 (56%), M 7 (19%), S 9 (25%)

A- Absent M-Mild S-Severe


Conclusions: LVI and MELF invasion are more frequent in FIGO grade 1 EEC with occult LN metastasis than in those without, but only LVI is independently associated with LN metastasis. The tumor cells in these lymph nodes often present as ITCs. Identifying these cases will further our understanding of the clinical significance of ITCs and micrometastases in EEC and, perhaps, yield information regarding which patients with clinically low stage EEC benefit most from LN dissection.
Category: Gynecologic & Obstetrics

Monday, March 22, 2010 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 156, Monday Morning