Perivascular Epithelioid Cell Tumor

Authors

Brad D. Barrows, D.O., M.S. (Fellow) and Deepti Dhall, M.D. (Faculty)

Subject: Liver tumor
Clinical History

The patient is a 57 year old female with history of benign spinal tumor status-post 3 resections, who was seen for progressive left lower extremity weakness and back pain. CT imaging identified an incidental 3 cm arterial enhancing mass in segment 3 of the liver with no evidence of cirrhosis, portal hypertension, or hepatomegaly. Physical exam and history were negative for gastrointestinal abnormalities. Lab studies showed normal liver function tests. Hepatitis serologies and alpha-fetoprotein were negative. Due to imaging findings suspicious for malignancy, left lateral segmentectomy was performed to remove the liver mass.

Additional Immunohistochemistry Studies

Tumor cells are negative for Hepar, CD163, Pancytokeratin, S100 (polyclonal), Synaptophysin, PAX-8, CD117, DOG-1, Desmin, Arginase-1, and SOX10.

Diagnosis

Perivascular epithelioid cell tumor (PEComa)

Discussion

Perivascular epithelioid cell neoplasms (PEComas) comprise a family of tumors including angiomyolipoma (AML) of the kidney, clear cell sugar tumor (CCST), lymphangioleiomyomatosis (LAM) of the lung, and rare tumors in other tissue locations. PEComa of the liver is an exceedingly rare, predominantly sporadic tumor occurring primarily in middle aged females (female to male ratio 7:1). PEComas are generally indolent tumors cured by excision. However, rare tumors with malignant features have been reported to demonstrate aggressive behavior including distant metastasis.

In 2005, Folpe and colleagues compiled 26 cases of PEComa from various body sites with clinical follow-up to characterize the behavior of these tumors. Tumor progression was observed in 6 patients with local recurrence and distant metastasis. Features of these 6 tumors (size > 8 cm, mitotic activity >1/50 HPF, and/or necrosis) were strongly associated with poor clinical outcomes (see reference).

Despite the rarity of these tumors, surgical removal and thorough histomorphologic examination is important to rule out potential malignant features and aid appropriate clinical management.

References

Folpe AL, Mentzel T, Lehr HA, Fisher C, Balzer BL, Weiss SW. Perivascular epithelioid cell neoplasms of soft tissue and gynecologic origin: a clinicopathologic study of 26 cases and review of the literature. Am J Surg Pathol. 2005 Dec;29(12):1558-75.

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