[1186] "Low Grade Uterine LMS" a Clinically Favorable, but Heterogeneous Group of Mesenchymal Tumors

R Soslow, O Zivanovic, L Jacks, M Hensley, E Veras. Memorial Sloan-Kettering Cancer Center, New York, NY

Background: Reliable pathologic predictors of clinical outcome have yet to be determined for uterine leiomyosarcoma (LMS). The literature suggests a correlation between tumor grade and clinical behavior. In this study, we reviewed LMS cases and focused on the clinicopathologic features of LMSs considered to be "low grade."
Design: The Murray Brennan Sarcoma Database was used to retrieve "low-grade" LMSs diagnosed between 1986 and 2009 (n=14). All available slides from hysterectomies were reviewed by two pathologists using Stanford criteria. "STUMP" was used as an abbreviation for "atypical leiomyoma with low recurrence rate" in this abstract.
Results: Only 29% (4/14) of all cases originally diagnosed as "low-grade" LMS met Stanford criteria for LMS. Four tumors were STUMPs, 2 of which were known to be recurrent and 1 high stage at presentation. 2 were leiomyoma variants. 3 were cellular spindle cell neoplasms requiring immunohistochemistry for confirmation of smooth muscle differentiation (two were suspected of being endometrial stromal sarcoma variants or malignant solitary fibrous tumor) and one was a cellular, benign endometrial polyp. 43% (6/14) of patients were NED, 21% (3/14) were AWD (2 STUMPs and one leiomyoma; range 59-295 months to recurrence) and 14% (2/14) were DOD (1 LMS and 1 probable endometrial stromal sarcoma; 15 and 18 months from diagnosis). Three patients died of unknown causes.
Conclusions: "Low grade LMS" is a heterogeneous group of mesenchymal tumors with favorable outcomes. When endometrial stromal tumor variants, STUMPs and other leiomyomas are excluded from this group, only rare LMSs remain, all of which are histologically indistinguishable from conventional LMS. The number of such tumors in this group precludes a statistical comparison of outcomes versus tumors diagnosed as conventional LMS. Whether patients diagnosed with recurrent STUMPs have low grade LMS is debatable.
Category: Gynecologic & Obstetrics

Monday, March 22, 2010 8:45 AM

Platform Session: Section D, Monday Morning


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