Other tumors

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

Revised: 4 January 2018, last major update August 2012

Copyright: (c) 2002-2018,, Inc.

PubMed Search: PEComa pancreas

Cite this page: Jain, D. PEComa. website. Accessed November 21st, 2018.
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

Images hosted on PathOut server:

Malignant tumor

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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