Bilateral synchronous tibial periosteal osteosarcoma with familial incidence.

Multifocal or multicentric osteosarcoma (OS) has been described as tumor occurrence at two or more sites in a patient without visceral metastasis. These may be synchronous (more than one lesion at presentation) or metachronous (new tumor developing after the initial treatment). The incidence of multifocal OS has ranged from 1.5 to 5.4% in large series, with the synchronous type being rarer. Similarly, periosteal OS is another rare subtype of surface OS and constitutes less than 2% of all OS. An 11-year-old female was diagnosed with bilateral synchronous tibial periosteal OS, which were confirmed by CT-guided biopsies. After neoadjuvant chemotherapy, the patient underwent a staged wide local resection of the tumors. The defect was reconstructed with a proximal tibial replacement on the left side and autologous bone grafting on the right side. The patient did well after surgery and is free of disease at 5.5 years of follow-up. However, her brother also developed a right tibial periosteal osteosarcoma 4 years after her index surgery. Genetic analysis of blood sample from both patients showed a similar missense mutation in at least one allele of TP53 gene (exon 8). To the best of our knowledge, a case of bilateral 'synchronous' periosteal OS with a familial incidence has not been reported before.