Journal of Pediatric Surgery Case Reports · Published 2026-07-11 · DOI 10.1016/j.epsc.2026.103308
Dailen Alonso, Stephanie Gruner, Ekene Onwuka
Introduction: Patients with Li-Fraumeni Syndrome (LFS), caused by germline TP53 pathogenic variants, carry a near-lifetime risk of developing multiple malignancies, including osteosarcomas. Extra-skeletal osteosarcoma (ESOS) is a rare subtype, representing about 1–4% of all osteosarcomas, occurring most commonly in older adults. Case presentation: A 16-year-old male with LFS and a history of multiple malignancies who subsequently developed a subcutaneous mass on his right posterior torso identified on surveillance MRI. Imaging confirmed the lesion was confined exclusively to the subcutaneous tissue with no involvement of underlying muscle or bone. Serial ultrasound confirmed rapid growth from 2.8 cm to 3.8 cm within one month. He underwent complete excisional biopsy with primary closure without complications and was discharged home the same day. Pathology report showed an extra-skeletal osteoblastic osteosarcoma with negative surgical margins. Restaging whole-body PET/CT and CT chest did not show evidence of metastatic disease. Genetic analysis of the specimen confirmed the underlying germline TP53 pathogenic variant but was uninformative for comparison to the prior skeletal osteosarcoma. Given the negative margins, absence of distant disease, and recent completion of platinum-based chemotherapy, the multidisciplinary tumor board elected surveillance over adjuvant chemotherapy, and close clinical and imaging follow-up every 3 months. At one year post-resection, the patient remains without evidence of disease recurrence. Conclusion: ESOS should be included in the differential diagnosis of patients with genetic cancer predisposition syndromes who develop superficial soft tissue lesions.
Abstract from DOAJ. Public domain (CC0 1.0).
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Alonso, D., Gruner, S., Onwuka, E. (2026). Extra-skeletal osteosarcoma in an Adolescent with Li-Fraumeni syndrome: A case report. Journal of Pediatric Surgery Case Reports. https://doi.org/10.1016/j.epsc.2026.103308