Low-grade central osteosarcoma of the hallux with a 7-year undiagnosed course: Case report

Background

Low-grade central osteosarcoma usually exhibits a long course with nonspecific symptoms, while the imaging and histological findings may be easily confused with a variety of benign fibroosseous lesions.

Materials and methods

A 15-year-old boy was referred for a painless swelling of the proximal phalanx associated with shortening of the right hallux. A benign cystic bone lesion complicated by a pathological fracture had been diagnosed on the radiographs at 8 and 10 years of age after sport injuries. He was referred for evaluation and treatment of the bone lesion. Magnetic resonance imaging and computed tomography were performed. A referral centre was contacted, since there was a strong evidence of malignancy. An open biopsy was suggested, which indicated bone malignancy. The patient was then referred to the specialized tumor centre. A new biopsy was performed there, since the previous sampling was considered insufficient or inadequate to secure a differentiation from fibrous dysplasia. It ensured the diagnosis of low-grade central osteosarcoma. Radical excision of the proximal phalanx and reconstruction of the defect with an iliac graft associated with arthrodesis of both the hallux metatarsophalangeal and interphalangeal joints was the treatment of choice. Disturbed wound healing necessitated hardware removal 4 months postoperatively. No further interventions were required in the follow-up.

Results and conclusion

Clinical and radiographic evaluation at 12 years confirmed no evidence of local recurrence or distant metastasis. The patient was satisfied with the final outcome and reported unrestricted participation to physical activities and sports.