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malignant epithelioid angiomyolipoma

Friday 23 December 2011

Highly aggressive epithelioid renal angiomyolipoma

Renal angiomyolipoma (AML) is hamartomas composed of blood vessels, smooth muscle and fatty tissue. In most cases, it is a tumor with benign behavior that may appear sporadically or be associated with tuberous sclerosis complex (TSC). Rare cases of clinically aggressive or malignant AML have been reported. These atypical variants of AML are histologically categorized as epithelioid AML.

Epithelioid AML is a recently recognized variant of AML that is characterized by the presence of polygonal cells with densely eosinophilic cytoplasm and varying degrees of nuclear atypia. These cells display positive immuno- reactivity for melanogenesis markers (HMB-45, MART1), and contain premelanosomes.

Extensive intratumoral hemorrhage and necrosis are more common in this variant than in the classic histological type.

No parameters have been developed for the correlation with prognosis, but patients with tumors showing necrosis, nuclear anaplasia, mitosis, and extrarenal dissemination have a poorer outcome.

The tumor consists predominantly of epithelioid cells with atypical nuclei and focal mitotic figures that stain strongly for HMB-45 and MART1.

Epithelioid AML is a rare tumor of unpredictable behavior.

See also

- angiomyolipomas
- epithelioid angiomyolipoma


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