To the Editor: A 71-year-old man presented with a firm erythematous painful swelling over the sternoclavicular region. He had undergone coronary artery bypass grafting (CABG) 18 months earlier.

A chest x-ray showed the presence of sternal wires and mediastinal clips from the surgery, and pleural thickening in the right costophrenic angle. There were no focal abnormalities seen on the x-ray when compared with pre-CABG radiographs.

A computed tomography scan of the chest showed a destructive lesion of the manubrium, with an associated soft tissue mass extending into the pectoralis muscle and anterior mediastinum. A sternal suture was noted within the lesion, and a separate surgical clip was identified in the suprasternal notch region (Box, A). Surgical exploration of the sternotomy wound revealed tumour in the muscle around the proximal sternum, with bone destruction. Histopathological examination of the tumour confirmed the presence of an osteosarcoma (Box, B). (A section of normal trabecular bone [Box, C] is shown for comparison.)

There have been few reported cases of primary sternal tumours. To our knowledge, primary osteosarcoma arising contiguous to a surgical suture has never been reported. It is unknown why the osteosarcoma originated in the part of the sternum that contained the sternal suture rather than originating de novo in another part of the bony skeleton. Chronic localised sternal inflammation or mechanical irritation of the proximal sternum by the suture may have been contributory factors in triggering carcinogenesis in this uncharacteristic site.1 However, the effect of trauma and mechanical stimulation on development of primary cancers and their metastases has never been proven. Patients who present with bony tumours frequently have a history of previous trauma to the area where the tumour develops. While there have been numerous reports suggesting some relationship between trauma/chronic inflammation and oncogenesis,1-5 there is no evidence that a single incident of trauma can cause cancer. The combination of trauma, in-situ metal and malignancy after CABG is rare, and there are currently no grounds for suspecting a direct relationship between them.

A: Computed tomography scan of the chest showing a destructive lesion in the cortex of the manubrium. A sternal suture, surgical clip and soft tissue mass are visible within the tumour (A = anterior, R = right). B: Histopathological section of osteosarcoma of the sternum. Pleomorphic and hyperchromatic cells are present in a disorganised immature bone matrix (osteoid) (haematoxylin and eosin stain; original magnification, × 20). C: Histopathological section showing normal trabecular bone of the sternum (haematoxylin and eosin stain; original magnification, × 2.5).