A80-4-28 Thoracic Endometriosis Followed by Pulmonary Pecoma: A Rare Dual Pathology in Lung Nodules

Abstract Perivascular epithelioid cell tumors (PEComas) are a rare group of mesenchymal neoplasms characterized by distinctive perivascular epithelioid cells that co-express melanocytic and smooth muscle markers with an incidence of 0.12-0.24 rate per 1,000,000 people. These tumors can arise in the uterus, retroperitoneum, gastrointestinal tract, and lungs. While most PEComas exhibit benign behavior, some display malignant potential with local invasion, recurrence, or distant metastasis. PEComas pose significant diagnostic and therapeutic challenges due to their rarity and variable clinical course. Here we present a case of pulmonary PEComa occurring in a patient with previous thoracic endometriosis. 66-year-old female with restrictive lung disease secondary to chronically elevated right hemidiaphragm, history of thoracic endometriosis status post thoracic resection, nicotine dependence was found to have a 13 mm right upper lobe nodule enlarging on low dose CT Chest surveillance imaging. A PET-CT revealed SUV max 3.4 with avid thoracic lymph nodes. Patient underwent Robotic Ion bronchoscopy. Transbronchial lung biopsy and mini bronchoalveolar lavage were sent from the right upper lobe. Surgical pathology revealed a population of large epithelioid cells with small oval nuclei arranged in an ill-defined nested growth pattern with delicate vascular stroma suggestive of either a perivascular epithelioid cell tumor (PEComa) or metastatic renal cell carcinoma. Immunohistochemical stains were focally positive for cathepsin-K and Melan-A and negative staining for SMA, HMB45, and PAX8 was consistent with PEComa.This patient with a history of thoracic endometriosis syndrome (TES) was found to have an enlarging PET avid right upper lobe lung nodule. It was initially suspected to be a recurrence of TES, however subsequent biopsy was consistent with a pulmonary PEComa. With 30 cases reported in the literature, PEComas are heterogeneous in clinical presentation, age preponderance as well as nature of tumors and outcomes. The main treatment is surgical resection with a long-term postoperative follow-up period for surveillance of recurrence. Some inoperable tumors are successfully treated with radiotherapy and chemotherapy. Patients with coexisting tuberous sclerosis complex (TSC) may benefit from mTOR inhibitors such as everolimus or sirolimus, although large-scale research remains limited. In our case, discussed this case in a multidisciplinary thoracic conference with a thorough evaluation of the risks and benefits of surgical resection versus IR-guided ablation and a referral to a sarcoma center for long-term monitoring and follow-up. A central database to track PEComas may help provide a better understanding of pathophysiology and management trends over time. This abstract is funded by: SELF