Liver and intrahepatic bile ducts - Perivascular epithelioid cell tumor (PEComa)

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Liver and intrahepatic bile ducts - Tumor

Benign tumors

Perivascular epithelioid cell tumor (PEComa)

Reviewers: Deepali Jain, M.D. (see Reviewers page)
Revised: 9 January 2013, last major update February 2012
Copyright: (c) 2004-2013, PathologyOutlines.com, Inc.

General
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● Mesenchymal tumor with dual melanocytic and myoid differentiation
● Related tumors include angiomyolipoma, clear cell sugar tumor of lung, lymphangioleiomyomatosis
● Rarely associated with tuberous sclerosis complex
● More common in females
● Rare malignant cases with metastasis (Arch Pathol Lab Med 2006;130:1219)

Case reports
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● 13 year old girl with tumor in ligamentum teres hepatis (Am J Surg Pathol 2000;24:1295)

Gross description
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● Well-defined, tan-white homogenous cut surface, no hemorrhage, no necrosis

Micro description
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● Nests or sheets of polygonal or oval cells with clear/finely granular cytoplasm, moderate nuclear atypia
● Well-developed capillary network, occasional perivascular hyalinization of sinusoidal vessels
● No mitotic figures, no invasive growth
● Criteria for malignancy: size > 5 cm, infiltration into surrounding tissue, high nuclear grade and cellularity, mitotic index > 1 per 50 hpf, necrosis, and vascular invasion (Hum Pathol 2010;41:1)

Micro images
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Various images

Positive stains
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● HMB45, MelanA/Mart1, microphthalmia transcription factor, PAS+ diastase sensitive, smooth muscle actin

Negative stains
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● Cytokeratin, desmin, EMA, S100, CD34, CD68, CD99, ER, PR

Electron macroscopy description
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● Numerous degenerated mitochondria, glycogen, thin filaments with focal densities, premelanosomes, subplasmalemmal densities

Differential diagnosis
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● Hepatocellular carcinoma, epithelioid angiomyolipoma

End of Liver and intrahepatic bile ducts - Tumor > Benign tumors > Perivascular epithelioid cell tumor (PEComa)

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