Elizabeth A. Montgomery, MD

Rare primary cutaneous PEComa shows a dermal-based clear cell neoplasm associated with small blood vessels image. There is a grenz zone separating the tumor from the overlying epidermis image.

High magnification shows a PEComa with epithelioid cells proliferating around vessels. There are scattered large nuclei image in this field, but no mitoses.



  • Perivascular epithelioid cell (PEC)

    • Thus, neoplasms are termed “PEComa”


  • Perivascular epithelioid cell tumor

  • Extrapulmonary sugar tumor

  • Monotypic epithelioid angiomyolipoma


  • Mesenchymal neoplasms composed of distinctive perivascular epithelioid cells; category includes

    • Angiomyolipoma (AML)

    • Clear cell “sugar” tumor of lung (CCST)

    • Lymphangioleiomyomatosis (LAM)

    • Clear cell myomelanocytic tumor of falciform ligament/ligamentum teres (CCMMT)

  • In many respects, PEComas are simply angiomyolipomas without fat

  • Subset displays overt histologic features of malignancy and malignant clinical behavior


Association with Tuberous Sclerosis

  • Genetic alterations of tuberous sclerosis complex (TSC), losses of TSC1 (9q34) or TSC2 (16p13.3) genes

  • Autosomal dominant inheritance

  • Benign tumors of brain (most common), kidneys, heart, eyes, lungs, and skin

    • Name comes from characteristic tuber or potato-like nodules in brain, which calcify with age and become hard or sclerotic

  • AML, CCST, and LAM are associated with tuberous sclerosis but not other types



  • Incidence

    • AML, CCST, LAM are rare

      • Other PEComas extremely rare

  • Age

    • CCMMT typically encountered in girls in late childhood

    • Most others seen in adults 50-60 years old

    • AML detected in younger patients in setting of tuberous sclerosis

  • Gender

    • Marked overall female predominance


  • Reported in multiple sites; rare in skin, but reported

    • Kidney, liver, falciform ligament, deep soft tissues of extremities, uterus, vulva, heart, gallbladder, gastrointestinal tract


  • CCMMT presents as painful abdominal mass

  • Uterine examples manifest as uterine bleeding

  • Most other categories of PEComas present as painless masses

  • Brain tumors in patients with tuberous sclerosis present with seizures, developmental delay, behavioral problems


  • Surgical excision

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Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on PEComas
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