Rhabdomyosarcoma-induced hypercalcemia in a nude mouse.
Hypercalcemia in nude mice with a rhabdomyosarcoma transplanted from a hypercalcemic patient is reported. The tumor had been transplanted to nude mice from a 15-year-old girl with hypercalcemia which appeared as the rhabdomyosarcoma developed and metastasized to the peritoneal and pleural cavities. The tumor was successfully transplanted to nude mice, which presented an elevated serum calcium level. No remarkable elevation of serum parathyroid hormone or 1 alpha, 25-dihydroxyvitamin D was found in the mouse with rhabdomyosarcoma. Injection of indomethacin restored the elevated serum calcium level to the normal range. The prostaglandin E2 level was approximately 15 times higher in the tumor-bearing mouse serum than in the control mouse serum. These data indicate that hypercalcemia in this patient can be ascribed to prostaglandin E2 produced by the rhabdomyosarcoma.