Ovary tumor
Other tumors not specific to ovary
Perivascular epithelioid cell tumor (PEComa)

Author: Nalini Gupta, M.D. (see Authors page)
Editor: Carlos Parra-Herran, M.D.

Revised: 30 June 2016, last major update February 2015

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Abdominopelvic sarcoma [title]
Cite this page: Perivascular epithelioid cell tumor (PEComa). PathologyOutlines.com website. http://pathologyoutlines.com/topic/ovarytumorpecoma.html. Accessed May 27th, 2017.
Definition / general
Pathophysiology
  • Cell of origin has not been definitively identified
  • Three hypotheses:
    • Undifferentiated cells of neural crest capable of dual smooth muscle and melanocytic differentiation
    • Myoblastic smooth muscle cells with a molecular alteration that causes expression of melanocytic markers (Arch Pathol Lab Med 2001;125:751)
Diagrams / tables

Classification by Folpe et al

Classification by Schoolmeester et al

Modified Folpe criteria

Clinical features
  • Abdominal / pelvic mass, pelvic pain
Diagnosis
  • Final diagnosis is by histology, immunohistochemistry and history of primary tumor elsewhere
  • History of tuberous sclerosis or other PEComa family tumors is helpful, but not always present
Radiology description
  • USG: solid adnexal mass
Prognostic factors
  • Primary PEC tumors
    • Classification of gynecologic PEComas as benign, uncertain malignant potential and malignant using tumor characteristics has been proposed by Folpe et al (Am J Surg Pathol 2005;29:1558) and Schoolmeester et al (Am J Surg Pathol 2014;38:176)
    • Conlon et al (J Clin Pathol 2015;68:418) applied both classification systems to 78 reported uterine PEComas, finding that a modified Folpe system (see below) allowed for better classification of tumors with good outcome as benign, and classification of all tumors with adverse outcome (metastases, recurrence, death of disease) as malignant

Case reports
Treatment
  • Primary PEC tumor:
    • Surgical resection of oligometastatic disease with or without adjuvant chemotherapy (anthracycline based)
    • Recently targeted therapies, most notably mTOR inhibitors are also utilized
Microscopic (histologic) description
  • Primary PEC tumor:
    • Sheets and nests of large polygonal cells with glycogen-rich clear or eosinophilic cytoplasm, moderately pleomorphic nuclei and delicate vasculature, resembling clear cell carcinoma
    • Mixture of epithelioid and spindle cells is common in variable proportions
    • Angiolymphatic invasion, coagulative necrosis, mitotic figures and intracytoplasmic brown pigment may be present (see criteria for malignancy above)
Microscopic (histologic) images

Images hosted on other servers:

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Clear cells resembling renal cell carcinoma

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High power

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Nodal metastases HMB45+

Positive stains
Electron microscopy description
  • Primary PEC tumor:
    • Hemidesmosome primitive junction, glycogen and stage I and II melanosomes
Molecular / cytogenetics description
  • Primary PEC tumor
    • PECs are linked to the tuberous sclerosis genes TSC1 and TSC2
    • This link is stronger for angiomyolipoma and lymphangioleiomyomatosis than for other members of the PEComa family
Differential diagnosis