[829] Pathologic Characteristics and Clinical Outcome of Renal Epithelioid Angiomyolipoma: A Multi-Institutional Experience Based on Primary Tumor Resections.

Wenlei He, John C Cheville, Peter M Sadow, Anuradha Gopalan, Samson W Fine, Hikmat A Al-Ahmadie, Yingbei Chen, Esther Oliva, Paul Russo, Victor E Reuter, Satish K Tickoo. Memorial Sloan-Kettering Cancer Center, New York, NY; Mayo Clinic, Rochester, MN; Massachusetts General Hospital, Boston

Background: Cases of metastases/recurrences in some renal epithelioid angiomyolipomas (E-AML) are well documented; hence E-AML is regarded as potentially malignant. The overall true incidence of aggressive behavior among all cases of E-AML remains undetermined. While the reported incidences of metastasis have ranged from 0 to >45%, the studies with high incidence have mainly consisted of cases received in consultation, or derived from case reports. To determine the true overall biologic behavior among all cases, we studied cases of E-AML from the time of resection of the primary tumors at 3 institutions with high nephrectomy volumes.
Design: Material from all renal AMLs, for which primary resection was performed at the 3 institutions over periods of 18, 30 and 30 years, respectively, was reviewed. Only the cases with pure or almost pure epithelioid histology were considered as E-AML for this study. Cases received in consultation were not included. Gross findings were obtained from the pathology reports, and clinical follow-up from medical records/prospectively maintained clinical renal data-base.
Results: Material was available on 435 renal AML cases with primary resections at these institutions. Eighteen (4.1%) of these were E-AML (80-100% epithelioid). The F:M ratio was 10:8, and the mean age, 51 years (range, 31-80 yrs). Mean tumor size was 7.5 cm (range, 1-19 cm). Other morphologic features currently available on 9 cases from 1 institution include, gross and microscopic tumor necrosis (5/9; 56% cases), mitotic rate <1 to 5/10 HPFs, and presence of pleomorphic giant cells (8/9; 89%). Over a mean follow-up of 55 months (range, 1-192 mths) available on 17/18 cases, none developed recurrence or metastasis. Sixteen of the patients were alive with no-evidence-of-disease (NED) at the time of last follow-up; one patient died of unrelated causes while NED.
Conclusions: 1. Pure/virtually pure epithelioid AML constitute approximately 4% of all resected AMLs. 2. While aggressive behavior in some E-AMLs is well-reported in literature, we observed no metastasis or recurrences in cases with primary resection over a period of long follow-up. 3. Our data indicates that the rate of aggressive clinical behavior of E-AML, as defined by the WHO classification, is lower than what the literature suggests; most cases follow a benign clinical course.
Category: Genitourinary (including renal tumors)

Tuesday, March 1, 2011 8:15 AM

Platform Session: Section A, Tuesday Morning

 

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