Severe hypercalcemia is a rare metabolic disorder in pediatric medicine. This report describes a rare case of severe hypercalcemia and its clinical manifestations in a 2-year-old toddler. The radiological findings caused by hypercalcemia and osteolysis were emblematic of the osteolytic lesions. Hypercalcemia led to massive pulmonary alveolar calcification. The hypercalcemia was successfully treated with pamidronate, a bisphosphonate drug class. Further investigation resulted in a diagnosis of acute lymphoblastic leukemia (ALL). The patient is currently on chemotherapy and has a favorable prognosis. Although severe hypercalcemia alone is an unusual finding as the first sign for ALL, this should be considered, not to mention the radiological images resulted from calcium deposits.