Laparoscopically resected perivascular epithelioid cell tumor of the ascending colon demonstrating submucosal tumor morphology: a case report

Abstract Background: The differential diagnosis for a colonic submucosal tumor (SMT) can include many types of cancer. We report a case of a perivascular epithelioid cell tumor (PEComa), a rare mesenchymal neoplasm that demonstrates SMT morphology, in the ascending colon.Case presentation: A mass was incidentally detected by computed tomography (CT) in a 53-year-old man. Colonoscopy revealed an SMT with central ulceration in the ascending colon, and 18F-fluoro-2-deoxy-D-glucose positron emission tomography CT demonstrated a high maximum standardized uptake value of 7.33. Preoperative diagnosis was inconclusive. Given the malignant potential of the tumor, we performed a laparoscopic right hemicolectomy with D3 lymph node dissection. The tumor was 5.5 cm × 4.1 cm and located in the submucosa and muscular propria. There was no lymph node metastasis (0/46). Based on the positive immunohistochemical stainings of both melanocytic (HMB45) and muscle (desmin) markers, we diagnosed the tumor as a PEComa. In the 17 months since surgical resection, the patient has not experienced recurrence, but careful observation should continue because of the malignant potential of the tumor.Conclusions: Although rare, a PEComa should be considered in the differential diagnosis of colonic SMT. Immunohistochemical staining of melanocytic and muscle markers is useful for the diagnosis.