Liver and intrahepatic bile ducts - tumor
Benign tumors / conditions
Perivascular epithelioid cell tumor (PEComa)

Author: Deepali Jain, M.D. (see Authors page)

Revised: 20 November 2017, last major update February 2012

Copyright: (c) 2002-2017,, Inc.

PubMed Search: Perivascular epithelioid cell tumor[TI] OR PEComa[TI] liver

Cite this page: Jain, D. Perivascular epithelioid cell tumor (PEComa). website. Accessed November 15th, 2018.
Definition / general
  • 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
Gross description
  • Well defined, tan white homogenous cut surface, no hemorrhage, no necrosis
Microscopic (histologic) description
  • 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)
Microscopic (histologic) images

Images hosted on other servers:

Various images

Negative stains
Electron microscopy description
  • Numerous degenerated mitochondria, glycogen, thin filaments with focal densities, premelanosomes, subplasmalemmal densities