Treatment of high-grade osteoblastic osteosarcoma of the humerus in a 5-year-old boy with cystic fibrosis: A case report.

Antineoplastic treatment of osteoblastic osteosarcoma in a patient with cystic fibrosis (CF) may harbor a high risk of neutropenia-associated complications, and, to the best of our knowledge, has not been previously reported. Diagnosis of CF was confirmed in a 6-week-old boy following pathological newborn screening. The patient had a stable course of CF under standardized continuous therapy. At the age of 5 years, osteosarcoma of the left proximal humerus was diagnosed without evidence of metastases. Neoadjuvant chemotherapy, including doxorubicin, cisplatin and methotrexate, was administered for 10 weeks. The patient tolerated this therapy relatively well, with a continuous antibiotic prophylaxis of cefuroxime without experiencing major complications; in particular, no pulmonary exacerbations were observed as a consequence of immunosuppression or mucosal toxicity. The tumor responded well, and amputation of the limb was avoided via the use of 'clavicle per humerus' osteosynthesis. Postoperatively, compartmental syndrome occurred, requiring management by fasciotomy. Adjuvant chemotherapy was applied thereafter again, without major toxicity that would have required dose reduction. Under intensive physiotherapy, the mobility of the left arm and hand was deemed to be satisfactory. The coincidence of CF with osteosarcoma is extremely rare, and, to the best of our knowledge, has not been previously described. Under antibiotic prophylaxis, antineoplastic treatment was possible without major complications during neutropenia.