Tumor induced hypercalcemia in a patient with mediastinal synovial sarcoma.

Tumor-induced hypercalcemia is a frequent complication of advanced cancers, but it has been rarely reported in patients with sarcoma. We report a 16 year-old boy presenting with polyuria, polydipsia and severe dehydration. Laboratory examination revealed severe hypercalcemia (serum calcium 23 mg/dl) which caused emaciation and was accompanied by low serum phosphorus and suppressed parathyroid hormone. Diagnostic imaging revealed a huge anterior mediastinal mass. Hypercalcemia was successfully treated with pamidronate, a bisphosphonate, and the patient underwent surgical resection. Pathological and immunohistochemical analyses confirmed a diagnosis of biphasic synovial sarcoma. To our knowledge, this is the first case of mediastinal synovial sarcoma presenting with hypercalcemia.