Chondroblastic osteosarcoma of the rib as a second primary malignancy following neuroblastoma: a case report

Second primary malignancies are a recognised long-term complication of childhood cancer. Osteosarcoma arising as a second malignancy is uncommon, and chest-wall involvement is rarer still, raising particular difficulties in achieving clear margins, reconstructing the thoracic wall, and separating a new tumour from recurrence of the original disease. We report chondroblastic osteosarcoma of the rib arising nine years after treatment for high-risk neuroblastoma.

A 12-year-old girl, treated at the age of three for stage III, N-MYC-amplified right adrenal neuroblastoma, presented with a two-week history of a painful right anterior chest-wall mass initially taken for a breast lump. Imaging showed an expansile mixed lytic-sclerotic lesion of the right fourth rib with chest-wall and pleural extension, and core-needle biopsy confirmed chondroblastic osteosarcoma (SATB2 positive; hormone-receptor negative). After neoadjuvant chemotherapy on the EURAMOS-1 protocol, en bloc resection of the right third to fifth ribs was performed with a porcine acellular dermal-matrix reconstruction. Positive deep, lateral, and medullary margins prompted re-excision a week later, which achieved clear margins.

Tumour necrosis of 80% indicated a Huvos grade II (poor) response, and, together with the initially positive margins, defined an unfavourable pathological profile. Radiotherapy during primary treatment was directed at the right adrenal region, ipsilateral to the later rib tumour, but the field and dose could not be retrieved, so a radiation-associated origin can be neither confirmed nor excluded; prior alkylating-agent chemotherapy is an alternative contributor.

New musculoskeletal complaints in a childhood cancer survivor warrant prompt cross-sectional imaging to distinguish a second malignancy from benign change; positive margins after chest-wall resection should prompt early re-excision, which can still secure local control; and a poor histological response with positive margins marks a patient for intensified surveillance.