A Perivascular Epithelioid Cell Tumor in the Ascending Colon: A Rare Case Involving a Patient With Tuberous Sclerosis.

Tuberous sclerosis (TSC) is a genetic disorder characterized by the development of benign tumors in various organs such as the brain, heart, lungs, kidneys, skin, and gastrointestinal tract. Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal tumors associated with TSC. Primary gastrointestinal PEComas are uncommon. This report describes a PEComa in the ascending colon of a patient with TSC and presents a review of the relevant literature. A 33-year-old female patient with a history of TSC presented with a 30-mm mass in the ascending colon that had remained stable for two years. A colonoscopy revealed a 30-mm submucosal tumor in the ascending colon, and non-neoplastic biopsy results were observed. Contrast-enhanced computed tomography revealed a 30-mm mass in the ascending colon with early contrast enhancement. After considering the differential diagnoses of PEComas, gastrointestinal stromal tumors, and leiomyomas/leiomyosarcomas, laparoscopic ileocecal resection was performed. A white extramural tumor that was covered with a capsule was observed in the ascending colon intraoperatively. The histopathological analysis results suggested a complex array of spindle cells. The immunohistochemistry results for alpha-smooth muscle actin, desmin, and human melanoma black (HMB)-45 were positive, and those for c-kit and S100 were negative, thus confirming the diagnosis of a PEComa. This case highlights the importance of considering PEComas when patients with TSC present with submucosal gastrointestinal tumors and the need for careful diagnostic evaluations of such cases.