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Epithelioid Angiomyolipoma

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  • Angiomyolipoma with predominant epithelioid morphology.
  • Like triphasic AML, some are associated with tuberous sclerosis and tuberous sclerosis complex genes.
  • Tumors in tuberous sclerosis tend to be large, multifocal and presents at younger age.
  • Histology:
    • Cohesive cells in nests or alveolar growth separated by thin septa and blood vessels ("carcinoma-like growth") (image A).
    • Spindle and epithelioid cells with fewer blood vessels (image B).
    • "Clear cells" with granular cytoplasm or eosinophilic cells (image C).
    • Nuclei appear high grade (image D) and mitosis is common.
    • Multinucleated pleomorphic giant cells.

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  • Immunohistochemistry:
    • Melanoma markers+ (HMB45+, Mart1+).
    • Muscle markers+ (smooth muscle actin+, desmin+) in spindle cells.
  • Unlike AML may recur and some cases metastasize and thus considered to be potentially malignant.
  • DDX:
    • Clear cell RCC: because of the clear cells and cohesive growth, but is epithelial marker keratin+ and melanoma marker-.