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Eble JN, Sauter G., Epstein JI, Sesterhenn IA - iarc

Eble JN, Sauter G., Epstein JI, Sesterhenn IA - iarc

Eble JN, Sauter G., Epstein JI, Sesterhenn IA - iarc

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Epithelioid angiomyolipoma<br />

M.B. Amin<br />

Definition<br />

Epithelioid angiomyolipoma (AML) is a<br />

potentially malignant mesenchymal neoplasm<br />

characterized by proliferation of predominantly<br />

epithelioid cells and is closely<br />

related to the triphasic (classic) AML.<br />

Epidemiology<br />

More than half of patients with epithelioid<br />

AML have a history of tuberous sclerosis<br />

(TS), which is a significantly higher association<br />

than classic AML has with TS<br />

{50,2036,1346}. Both sexes are equally<br />

affected similar to classic AML occurring in<br />

TS patients. The mean age of diagnosis is<br />

38 years {649,50,463,466,593,1606,1634}.<br />

Clinical features<br />

Patients are frequently symptomatic, presenting<br />

with pain; some patients are discovered<br />

during TS follow-up. Imaging<br />

studies closely mimic renal cell carcinoma<br />

because of the paucity of adipose tissue<br />

{1289,463,224}.<br />

Macroscopy<br />

Tumours are usually large, with infiltrative<br />

growth and a grey-tan, white, brown or<br />

haemorrhagic appearance. Necrosis<br />

may be present. Extrarenal extension or<br />

involvement of the renal vein/vena cava<br />

may occur.<br />

Histopathology<br />

There is a proliferation of epithelioid cells<br />

with abundant granular cytoplasm<br />

arranged in sheets, often with perivascular<br />

cuffing of epithelioid cells. Many of the<br />

reported cases were initially misdiagnosed<br />

as a high grade carcinoma. Tumour cells<br />

are round to polygonal with enlarged vesicular<br />

nuclei often with prominent nucleoli.<br />

A<br />

B<br />

Fig. 1.100 Epithelioid angiomyolipoma. A Epithelioid angiomyolipoma is typically composed of a mixture of polygonal and spindle cells of variable size. Inflammatory<br />

cells often are mingled with the neoplastic cells. B Focally ganglion like and multinucleated cells are present.<br />

A<br />

B<br />

Fig. 1.101 Epithelioid angiomyolipoma. A Marked nuclear atypia and mitotic figures may be present. B Immunohistochemical reaction with HMB-45 shows numerous<br />

positive cells.<br />

68 Tumours of the kidney

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