Abstract
Abstract
Giant cell tumor of bone (GCTB) rarely arises in the rib, and anterior rib involvement may mimic malignant chest-wall tumors. A 44-year-old woman presented with a palpable mass in the left anterior chest wall. Computed tomography (CT) revealed an osteolytic mass arising from the anterior left third rib, enlarging from 31 to 55 mm over ~2 months. Magnetic resonance imaging showed diffusion restriction, and fluorodeoxyglucose positron emission tomography/CT demonstrated intense uptake with a maximum standardized uptake value of 15.7, raising suspicion for malignancy. Needle biopsy suggested GCTB, but malignancy could not be excluded. Wide resection of the left second to fourth ribs was performed. Histology showed no sarcomatous transformation, and nuclear histone H3.3 with a glycine-to-tryptophan substitution at amino acid position 34 positivity in mononuclear tumor cells supported the diagnosis of GCTB. The patient remained recurrence-free for ~2 years. Anterior rib GCTB can mimic malignancy, requiring integrated radiological and pathological evaluation.