Perirenal PEComa: Computed Tomography Findings and Differential Diagnosis

Abstract

The World Health Organization defines perivascular epithelioid cell tumors (PEComas) as mesenchymal tumors and tumor-like conditions composed of epithelioid cells with a perivascular distribution. These tumors may show benign or malignant histology and/or biological behavior. However, the pathological features of malignancy may not correlate with biologic aggressiveness, and the criteria for malignancy are not clearly defined. Abdominopelvic PEComas are very rare and have been reported in various locations, including kidney, liver, pancreas, gastrointestinal tract, genitourinary tract, peritoneum, and retroperitoneum. Cross-sectional imaging techniques, including computed tomography (CT) may play an important role in the accurate detection and characterization of these tumors. We present the third case of an extremely rare PEComa with perirenal location, discuss CT findings and differential diagnosis.

Perirenal Perivascular Epithelioid Cell Tumor (PEcoma) with Pulmonary Micro Invasive Adenocarcinoma: A Case Report and Literature Review

“…Finally, pathology of the pulmonary mass suggested MIA (<0.6 cm invasion), and immunohistochemistry stains suggested that the perirenal neoplasm was not the metastasis of pulmonary MIA but the primary PEComa. Similar to the other case, 7 as most PEComa showno specific symptoms, the distinction between one primary tumor with metastatic sites and concomitantly primary tumors was difficult when imaging detected multiple lesions. On this occasion, the acquisition of specimens in multiple lesions is crucial for the diagnosis and the selection of the treatment.…”

“…On the other hand, for patients with PEComa that shows malignant phenotype without resectability, both mTOR inhibitor and chemotherapy might not considerably improve the survival rate. 7 …”

Radiological findings of two neoplasms with perivascular epithelioid cell differentiation

“…Presence of microscopic fat is diagnostic of angiomyolipomas of the kidney, which belong to this new group of tumors; however, this finding has not been seen in PEComas at other organs and locations. The heterogeneous appearance of these tumors is in part related to areas of cystic degeneration and/or necrosis and explains heterogeneous enhancement on cross-sectional studies with avid enhancement in solid portions of the tumors; this description has been utilized in multiple case reports and large cohort studies of PEComas [2] , [3] , [4] . Encapsulation has been reported with some of the tumors, especially with nonaggressive histology, resulting in description of circumscribed mass with solid and cystic components [2] , [3] , [4] .…”

“…First, both masses are circumscribed, without involvement of the adjacent organs or structures. Additionally, both masses contained solid and cystic components, as has been commonly reported [4] , [5] , with areas of high T1 signal intensity internally, representing hemorrhagic or proteinaceous fluid; this description has not been utilized in prior case reports and studies. Neither mass contained microscopic or macroscopic fat.…”

Multifocal retroperitoneal and pelvic PEComas mimicking liposarcoma: A case report and review of literature

“…Many PEComas follow a benign course, sufficiently curable with surgical resection alone; a minority have shown aggressive behavior, with local recurrence and/or distant metastases [3] , [4] , [19] . As their natural history is not well-characterized, periodic long-term clinical and radiological surveillance is strongly recommended after initial treatment.…”