Giant Cell Reparative Granuloma

A lytic, expansile giant-cell-rich lesion of a phalanx is most likely a giant cell reparative granuloma, which is a benign, reactive giant-cell lesion that characteristically affects the small bones of the hands and feet, and also the jaws, and is regarded as part of the giant-cell-lesion-of-small-bones spectrum overlapping with the solid aneurysmal bone cyst. However, I would not assume that, because the key differential is giant cell tumour of bone. Histologically, the reparative granuloma shows a fibrous stroma with osteoclast-type giant cells that are unevenly distributed, clustered around areas of haemorrhage, together with reactive woven bone and haemosiderin, whereas a giant cell tumour of bone shows large giant cells evenly distributed throughout a mononuclear neoplastic stroma, and is locally aggressive - and importantly is rare in the hand. I would also check the serum calcium and PTH to exclude a brown tumour of hyperparathyroidism, and consider aneurysmal bone cyst. So I would image the lesion, send biochemistry, and obtain histology reviewed at a centre experienced in bone tumours. Management of a confirmed reparative granuloma is curettage with bone grafting, which is usually effective, but there is a notable recurrence rate, so I would follow the patient up. If the lesion recurs or behaves aggressively, I would re-confirm the diagnosis with a fresh, experienced pathological review and consider more extensive excision, occasionally amputation of the digit tip, because a so-called recurrent reparative granuloma may in fact prove to be a giant cell tumour of bone, as has been reported.