Neuroblastoma can be the cause in this case.It is the most common intra-abdominal malignant solid tumor in children.Around 50% of the patients present within the first 2 years.The patient may be asymptomatic with an incidentally diagnosed abdominal mass.The most common site for neuroblastoma is adrenal medulla,which in this case,is responsible for the calcification near the left kidney. A lump can be found in a variety of locations in a child with neuroblastoma. The abdomen is the most common location to find a mass. The child may present with swelling around the location of the mass, have complaints of discomfo or pain, and may refuse to eat. The lump maybe palpable, but is often not painful or tender to the touch. The child may also have high blood pressure from the tumor pressing on the abdominal aoa or other large blood vessels in the abdomen. Reference:Essential pediatrics-Ghai,8th edition,page no:616