<B>Wilms_tumor </B>

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Wilms_tumor

Etiology:

• Evidence is strong for a genetic/developmental etiology.

Pathogenesis:

• The tumor may arise as a result of failure of blastemal tissue to differentiate into normal renal structures.

Epidemiology:

• Occurs in children, usually under age 5.
• Peak incidence between ages 1 and 3.
• Occurs in approximately 7 in a million children per year in the U.S.
• Occurs as part of WARG syndrome (wilms tumor, aniridia, retardation, genital abnormalities).
• Occurs as part of Denys-Drash syndrome (gonadal dysgenesis and nephropathy leading to renal failure).
• Occurs as part of Beckwith-Wiedemann syndrome (organomegaly, hemihypertrophy, renal cysts, adrenal cytomegaly).

General Gross Description:

• At the time of detection, Wilms tumors are usually large and dwarfs the native kidney.
• The cut surface is usually soft, fleshy and brain-like.
• Irregular areas of hemorrhage and necrosis may be present.

General Microscopic Description:

• The classic Wilms tumor is triphasic showing areas that are blastemal (non-descript undifferentiated small round cells), areas that show epithelial differentiation (tubules, glomeruloid structures) and areas that show stromal differentiation (spindle shaped cells, skeletal muscle).
• Mitotic figures are usually plentiful.

Clinical Correlations:

• The clinical presentation is that of a large abdominal mass in a child, usually 1 to 5 years old

References:
•Robbins Pathologic Basis of Disease. (Cotran, Kumar and Robbins, Eds.) 5th Edition, pp. 462-464.