RESUMEN
We present the first reported case of a child with familial expansile osteolysis syndrome (FEO) who developed osteogenic sarcoma (OS) of the iliac bone. A 17-year-old adolescent presented with pain and a mass on the left pelvis. He was from a family with several members who had been diagnosed with FEO, from which he also suffered. The median life expectancy of affected members of the family was reported as 25 to 30 years, with death ensuing as a result of various respiratory and cardiac complications of severe skeletal deformations, characteristic of increased bone turnover as seen in FEO. Biopsy of the patient's mass revealed chondroblastic OS. He was treated according to the P9754 protocol for patients with newly diagnosed nonmetastatic OS. Chemotherapy consisted of HD-MTX, ifosfomide, doxorubicin, and cisplatin. Complete resection of the tumor was carried out, but the patient subsequently developed metastatic disease and died (histologic response to neoadjuvant chemotherapy-85%). The patient's alkaline phosphatase level that was highly elevated before the start of chemotherapy, dropped significantly during treatment, with repeated elevation soon after definitive surgery, while he was recuperating and not on treatment. We speculate that chemotherapy affected not only the malignant cells of OS but normal osteoblasts as well, with a decreasing level of alkaline phosphatase even in the absence of any clinical and radiographic signs of OS. We also think that increased bone turnover, characteristic of a condition such as FEO, may facilitate de novo development of OS.
