A 74-year-old man presented to Chengdu Second People's Hospital with a 1-month history of painful erythema on the left thumb (figure A) and nodules on the left forearm (figure B). More than 2 months ago, he had scraped fish scales at home before the onset of symptoms. 9 years previously, the patient was diagnosed with chronic lymphoblastic leukaemia, and 2 years previously he had been prescribed an ongoing therapy of chlorambucil 4 mg in the morning and 2 mg in the evening, and prednisone 5 mg per day, which he was still receiving at the time of presentation.

FigureSkin manifestation of M haemophilus infection and pathogen

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(A) Painful erythema on the left thumb. (B) Bead-like nodules on the left forearm after biopsy. (C) Acid-fast bacilli found in the thumb pus. (D) Improvement of the skin after 2 months treatment.