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Malignant Epithelioid Angiomyolipoma of the Kidney (Malignant Perivascular Epithelioid Cell Neoplasm)

      An adult female with abdominal discomfort was found to have a renal mass and paraortic lymphadenopathy on computed tomography of the abdomen and pelvis. The tumor was resected and diagnosed as malignant epithelioid angiomyolipoma (malignant perivascular epithelioid cell neoplasm) of the kidney. The tumor was associated with matted lymph node metastasis.
      What statement is least accurate?
      • a.
        Renal angiomyolipomas are the members of the tumor family generally known as perivascular epithelioid cell tumors
      • b.
        Although most renal angiomyolipomas have benign behavior, epithelioid renal angiomyolipomas, particularly those with necrosis and marked nuclear atypia, may behave in a malignant manner with metastases
      • c.
        Renal angiomyolipomas can be associated with tuberous sclerosis complex
      • d.
        Perivascular epithelioid cell tumors occur only in the liver and kidney
      Answer: d. Perivascular epithelioid cell tumors occur only in the liver and kidney
      Perivascular epithelioid cell tumor is a term used for tumors composed of perivascular epithelioid cells in various sites, including renal and extrarenal angiomyolipomas, hepatic angiomyolipoma, clear cell sugar tumor of the lung, primary extrapulmonary sugar tumor, lymphangiomyomatosis, abdominopelvic sarcoma of perivascular epithelioid cells, clear cell myomelanocytic tumor, and genitourinary perivascular epithelioid cell tumor. These tumors can be associated with tuberous sclerosis complex.
      • Bissler J.J.
      • Christopher Kingswood J.
      Renal manifestation of tuberous sclerosis complex.
      Renal angiomyolipomas usually behave in a benign manner. However, epithelioid renal angiomyolipomas may behave in a malignant manner with metastases, particularly in cases with necrosis and marked nuclear atypia.
      • Hornick J.L.
      • Fletcher C.D.
      PEComa: what do we know so far?.
      These tumors are differentiated from renal cell carcinomas by their immunopositivity for MelanA and HMB45.

      References

        • Bissler J.J.
        • Christopher Kingswood J.
        Renal manifestation of tuberous sclerosis complex.
        Am J Med Genet C Semin Med Genet. 2018; 178: 338-347
        • Hornick J.L.
        • Fletcher C.D.
        PEComa: what do we know so far?.
        Histopathology. 2006; 48: 75-82