BONE-TUMOR EXERESIS FOR SECONDARY RICKETS TREATMENT - A CASE-REPORT

Purpose of the study Rickets secondary to bone or soft tissue tumors a re rare in children. Majority of the reported cases occured in adults older than thirty. This entity can be cured after tumor removal. The a uthors present a case in a ten year boy and literature review. Materia l A ten year boy complained of diffuse bone and muscle weakness for tw o years. A diagnosis of arthritis was made but the patient continued t o complain. Serum calcium level was normal (2.33 mmol/l), phosphorus w as very low (0.43 mmol/l), serum alkaline phosphatase was high, parath yroid hormon and vitamin D level were normal. Urinalysis showed abnorm al phosphate excretion. Methods The absence of malabsorption, no famil y history of rickets or hypophosphatermy presence of a marked excess o f urinary phosphate, very low serum phosphate and normal serum calcium , vitamin D and parathyroid hormon levels led us to consider a diagnos is of tumor induced osteomalacia. Radiographs showed a large round rad iolucent lesion in the left superior pubic ramus and generalized demin eralisation. Results We performed a complete tumor resection and the s pace was filled with bone graft. On histopathologic examination it was a benign mesenchymal tumor. Rapid reversal of biochemical anomalies, radiographs anomalies and clinical manifestation were observed after c omplete tumor resection. Discussion The authors have described the tum or, the osteomalacia and the pathogenis of tumor rickets. Histological ly the most common causative tumors were vascular tumors, mesenchymal tumors and non ossifying tumors. The tumor were of bone or soft tissue origin. Clinical symptoms were muscular weakness, bone and muscle pai n. Biochemically there is a very low phosphate level, a normal serum c alcium level as well as a normal vitamin D and PTH level. There is a s ignificant high level of urinal phosphate. The mechanism proposed to e xplain oncogenic osteomalacia includes tumor secretion of phosphaturic substance other than PTH and calcitonin. Another hypothesis is a subs tance interfering with normal vitamine D metabolism. The pathogenesis is not clearly defined. Conclusion Regardless to the mechanism of oste omalacia, complete removal of the tumor will cure the patient. A dilig ent search for tumors should be done in patients with vitamin D resist ant rickets.