Wilms tumor - most common presenting symptom
Wilm's tumor (Nephroblastoma) 

Most common malignant tumor of kidney,
80% of tumor present below 5 year of age.

Presentation 

Asymptomac abdominal mass (M. C.).
Haematuria (10-25%).
Hypertension (25%).
Abdominal pain (30%).
Fever (20%).
Haematuria
Asymptomac abdominal mass
Abdominal pain
Headache