PEComa with metastatic pulmonary embolism upon presentation: A case report.

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms with an incidence of approximately 0.3 per million. They exhibit histological and immunohistochemical features that overlap with angiomyolipomas and clear cell tumors. PEComas predominantly affect women and are either classified as being linked to tuberous sclerosis or are classified as PEComas-Not Otherwise Specified which means that their origin is not linked to tuberous sclerosis. They often arise from the genitourinary tract. The malignant potential of these tumors is determined by factors such as size (>5 cm), mitotic activity, necrosis, and vascular invasion. Treatment involves resection and mTOR inhibitors. Standardized treatment protocols are lacking due to rarity of the pathology, so each occurrence is considered on a case-by-case basis. A 69-year-old woman with dyspnea underwent CT imaging, revealing a large renal mass, a liver lesion, lung nodules, enlarged hilar lymph nodes, and a pulmonary embolism. Subsequent FDG-PET-CT confirmed FDG-avid lesions, with uptake of the pulmonary emboli suggesting their malignant origin. A subsequent liver biopsy diagnosed a malignant PEComa. MRI demonstrated T2 hyperintensity, restricted diffusion and postcontrast enhancement. Treatment with Everolimus resulted in a partial response of all lesions on 3-month follow-up imaging. PEComas were first recognized by the World Health Organization in 2002 and often present with nonspecific symptoms. They may manifest with metastatic disease at the time of diagnosis. This case highlights metastatic pulmonary embolism as an initial presentation. PEComas pose diagnostic challenges due to their nonspecific imaging findings and varied presentations. This case underscores their potential for aggressive behavior and the role of mTOR inhibitors. Despite successful treatment, the prognosis remains variable, necessitating multidisciplinary management and long-term surveillance. Early biopsy and molecular profiling are critical for optimizing outcomes. With this case report, we hope to bring attention to the possibility of pulmonary emboli being of metastatic origin when found in the context of a pre-existent oncological disease.