Acute haemorrhage into a subperiosteal ganglion.

Subperiosteal ganglion is uncommon and usually presents as an asymptomatic cystic mass attached to a bone. It may also cause aching pain (Fisk 1949; Byers and Wadsworth l970)or be an incidental radiographic finding (Grange 1978). Previous reports have emphasised the characteristic radiological appearance of cortical erosion with spicubes of subperiosteal new bone (Heyse-Moore and Grange 1979). We present a case in which bleeding into a subperiosteal ganglion combined with the radiographic appearances were wrongly assumed to be due to an atypical bone infection or tumour. Case report. A 68-year-old man was referred with a history that a bong-standing cystic lesion over his right tibia had enlarged rapidly and had become hot, red and painful. He had been started on oral penicillin. A subsequent radiograph (Fig. 1) showed patchy bone erosion and a small area of new bone formation. A provisional diagnosis of bone infection or tumour was made and he was referred for biopsy. At operation a subperiosteab ganglion was found and removed. The contents of the ganglion were heavily bloodstained. Histology confirmed benign subperiosteal new bone formation with haemosiderin staining. The patient made an uneventful recovery. Discussion. It is perhaps surprising that there have been no previous case reports of acute bleeding into a subperiosteab ganglion. Any lesion which strips the periosteum from bone, however slowly, is obviously liable to cause bleeding from the periosteab vessels. A simple subperiosteal ganglion is a diagnostic puzzle in that a lesion that is entirely benign clinically can show suspicious radiological features. We feel that this case is worth reporting as it demonstrates that haemorrhage into a subperiosteal ganglion may mimic more serious pathology both clinically and radiologically and therefore needs to be considered as part of the differential diagnosis.