Other tumors

Topic Completed: 1 August 2012

Minor changes: 24 July 2020

Copyright: 2002-2020,, Inc.

PubMed Search: PEComa pancreas

Deepali Jain, M.D.
Page views in 2019: 1,891
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Cite this page: Jain D. PEComa. website. Accessed August 6th, 2020.
Definition / general
  • Perivascular Epithelioid Cell tumor
  • Rare, also called clear cell "sugar" tumor
  • Well vascularized neoplasm composed of large, clear, epithelioid smooth muscle cells, HMB45+, MelanA+, smooth muscle actin+, keratin-
  • Concept first proposed in 1992 (Am J Surg Pathol 1992;16:307)
  • Arises from perivascular epithelioid cells, which also cause lymphangioleiomyomatosis, angiomyolipoma (renal and extrarenal, Virchows Arch 2008;452:119), related tumors of falciform ligament / ligamentum teres, skin (Histopathology 2005;46:498), uterus (Mod Pathol 2005;18:1336) and other viscera and soft tissue
  • Origin: no known normal counterpart to perivascular epithelioid cell
Case reports
Microscopic (histologic) description
  • Large epithelioid cells, clear or eosinophilic granular cytoplasm containing glycogen with nuclear pleomorphism but no mitotic activity
  • May have brown dusty pigment suggestive of melanin
  • No glandular growth or sarcomatous features
  • Malignant appearing tumors may have large zones of necrosis and nests of malignant cells with marked cellular pleomorphism and mitotic activity
Microscopic (histologic) images


Malignant tumor

Images hosted on other servers:

Well vascularized neoplasm composed of epithelioid smooth muscle cells with clear cytoplasm rich in glycogen



A: well demarcated tumor adjacent to normal pancreas (left - lower corner); tumor is composed of sheets of epithelioid to spindled cells with abundant clear to granular cytoplasm and mild to moderate nuclear pleomorphism;
B: MelanA+; C: SMA+

Negative stains
Electron microscopy description
Differential diagnosis
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