A 45‐year‐old woman presents to her GP with a 4‐week history of increasing fatigue. She has also noticed that the whites of her eyes have become yellow. On direct questioning, she has had flitting joint pains over the last 6 months, which she has put down to ‘growing older’. She is otherwise well and has no relevant past medical history. On examination, she was mildly jaundiced with an erythematous rash over her cheeks and the bridge of her nose. A 2 cm, non‐tender spleen could be palpated but there was no lymphadenopathy or hepatomegaly. Her blood results are as follows:

Film: polychromasia, spherocytes (Fig.0005)

Fig. 0005. The peripheral blood film.