Epithelioid angiomyolipoma: a morphologically distinct variant that mimics a variety of intra-abdominal neoplasms

Arch Pathol Lab Med. 2011 May;135(5):665-70. doi: 10.5858/2009-0637-RSR.1.

Abstract

This review examines the histopathologic, immunohistochemical, ultrastructural, and molecular biologic features of epithelioid angiomyolipoma (EAML), with an emphasis on the differential diagnosis of intra-abdominal EAML. Epithelioid angiomyolipoma is an uncommon mesenchymal tumor with malignant potential, frequently associated with tuberous sclerosis complex. Histologically, EAML is characterized by sheets or nests of large polygonal epithelioid cells with abundant eosinophilic or occasionally clear cytoplasm, often with prominent nucleoli, and EAML may include multinucleated and markedly pleomorphic forms. As these tumors share a distinctive perivascular epithelioid cell phenotype, they belong to the PEComa tumor family. Nearly all EAMLs show immunoreactivity for both melanocytic and myoid markers. Ultrastructurally, EAMLs show evidence of melanogenesis by the presence of premelanosomes. Epithelioid angiomyolipoma can pose significant diagnostic challenges as it mimics morphologically a variety of neoplasms including renal cell carcinoma, renal oncocytoma, adrenal cortical neoplasm, epithelioid smooth muscle tumor, epithelioid peripheral nerve sheath tumor, epithelioid gastrointestinal stromal tumor, epithelioid melanoma, hepatoblastoma, and hepatocellular carcinoma. The variation in immunophenotype in these tumors requires a prudent use of immunohistochemistry, which may occasionally need complementation by electron microscopy to establish the correct diagnosis.

Publication types

  • Review

MeSH terms

  • Abdominal Neoplasms / genetics
  • Abdominal Neoplasms / metabolism
  • Abdominal Neoplasms / pathology*
  • Angiomyolipoma / genetics
  • Angiomyolipoma / metabolism
  • Angiomyolipoma / pathology*
  • Biomarkers, Tumor / genetics
  • Biomarkers, Tumor / metabolism
  • Epithelioid Cells / metabolism
  • Epithelioid Cells / pathology*
  • Humans
  • Immunohistochemistry
  • Soft Tissue Neoplasms / genetics
  • Soft Tissue Neoplasms / metabolism
  • Soft Tissue Neoplasms / pathology*

Substances

  • Biomarkers, Tumor