Primary localized malignant PEComa treated with surgery: A report of a large series of patients treated in a referral institution.

Abstract

11582 Background: Perivascular Epithelioid Cell Tumors (PEComa) are mesenchymal neoplasms with a characteristic myomelanocytic immunophenotype. These tumors exhibit a broad anatomic distribution, and aggressive clinical behavior has been correlated with histological features such as tumor size and increasing mitotic activity. PEComas arising from the kidney are referred to as angiomyolipomas and usually lack metastatic potential, whereas epithelioid angiomyolipomas do have metastatic potential. Until now, only case reports or a limited number of patients have been documented in the literature, resulting in a lack of data regarding their clinical behavior. In this study, we present the outcomes of a large series of patients (pts) with primary localized malignant PEComa. Methods: This is a retrospective study involving all consecutive pts of any age affected by primary and localized malignant Pecoma surgically treated with curative intent at our institution from January 2000 to December 2023. Eligible pts had a pathologically confirmed diagnosis of malignant Pecoma. We present the outcome results in terms of Disease-Free Survival (that includes Local Recurrence (LR), Distant Metastases (DM), or death as first events) and Overall Survival (OS). Due to the low number of events only univariable analyses were performed. Results: 48 patients (19/48 M; 29/48 F) were identified. Median age at surgery was 50 yrs (range 18-80). Primary site was extremity and trunk in 19/48 pts, retroperitoneum in 13/48 pts and other in 16/48; median size of tumor was 11 cm (range 1-30 cm). At a m-FU of 57 mos (IQR:22-116), 8 pts died. Five- and 10-yr OS was 81.6% [95% Confidence Interval (CI): 70.1-94.9%)] and 77.3% (CI: 64.2-93.0%), respectively. One patient developed LR as first event, 9 developed DM and 3 died without any LR and DM; 3 and 1 patients developed DM as 2nd and 3rd event, respectively. Five- and 10-yr DFS was 69.4% [CI: 56.3-85.6%] and 65.1% (CI: 50.9-83.1%). Predictors of higher risk of DFS were age (>64 yrs old) and site of origin [p=0.5; HR trunk and arms: 1.2 (CI: 0.38-3.81) vs. retroperitoneum and 3.49 (CI: 0.43-28.37) vs other]. Conclusions: In this series PEComas have a 30% risk of recurrence at 5 years. While age and the site of origin are associated with the natural history of the disease, better pathologic criteria are needed to stratify their risk.