Haemothorax from aneurysmal bone cyst of the spine.

Aneurysmal bone cyst (ABC) is a benign bone tumour characterised by rapidly expanding osteolysis. The nomenclature was proposed by Jaffe and Lichtenstein (1942), who also determined the nature of the lesion. Between 9% and 12% of all aneurysmal bone cysts occur in the spine (Campanacci, Capanna and Picci 1986), presenting with back pain and symptoms resulting from cord or root compression and from vertebral collapse. Haemothorax is an unusual presentation and to our knowledge has never been reported in the English literature. Case report. A nine-year-old girl presented with a onemonth history of increasing dyspnoea and dull upper back pain, radiating to the left hemithorax. Radiographs showed a large quantity of fluid in the left pleural cavity (Fig. 1). This was drained and 1500 ml of haemorrhagic fluid was removed ; histologically there was no evidence of malignancy. Further radiographs indicated a tumour mass in the left superior and posterior part of the mediastinum and a CT scan showed a cystic lesion involving the body of the fourth thoracic vertebra (Fig. 2). Over the next six days, recurrence of the haemothorax was associated with a precipitous drop in the haemoglobin level requiring transfusion of two units of blood. Left thoracotomy revealed a tumour mass, 6 x 10 cm in diameter, originating from the upper thoracic spine ; the tumour seemed to have penetrated the pleura developing loose adhesions with the left lung. The pleura was incised longitudinally over the spine, the segmental vessels proximally and distally were ligated and the whole tumour mass was exposed. It had a cystic appearance and a very thin bony shell. Removal of the periosteum revealed a crater 1 x 2 cm in diameter, containing clotted blood which was removed ; this was followed by profuse haemorrhage. At the base of the crater was the body of the fourth thoracic vertebra. There was erosion