Surgical case reports
Malignant Perivascular Epithelioid Cell Tumor Originating from the Transverse Mesocolon
By Yokota R, Ohta R, Takeda K and 5 others.
Abstract
Introduction
Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms with melanocytic and smooth muscle differentiation. Primary mesenteric PEComas are exceptionally uncommon and usually cannot be diagnosed from imaging alone. We report a case of malignant PEComa arising from the transverse mesocolon.
Case presentation
A 34-year-old woman was referred to our department after abdominal ultrasonography showed a large intra-abdominal mass. Contrast-enhanced CT revealed a 15-cm heterogeneous, hypervascular mesenteric tumor with internal necrosis and feeding vessels from the superior mesenteric artery. MRI showed no continuity with the uterus or ovaries. Because percutaneous biopsy was considered to carry a substantial risk of bleeding and dissemination, the tumor was resected for diagnosis and treatment. Laparotomy demonstrated a transverse-mesocolic tumor directly invading the transverse colon; transverse colectomy with en bloc tumor resection was performed. Histopathological evaluation showed pleomorphic epithelioid cells, marked nuclear atypia, coagulative necrosis, vascular invasion, and frequent mitoses. The tumor was positive for HMB-45, Melan-A, and smooth muscle actin and negative for TFE3, supporting malignant PEComa. The postoperative course was uneventful, and the patient remained free of recurrence 4 months after surgery.