Bronchial carcinoma presenting as autoimmune haemolytic anaemia

A 68-year-old man presented with autoimmune haemolytic anaemia. Investigation revealed underlying bronchial carcinoma. A positive direct Coombs' test failed to revert to negative after removal of the primary tumour. This suggested the presence of metastases which was subsequently shown. The possible significance and origin of the autoantibody is discussed.