Summary

Mycobacterium malmoense is recognised as an environmental pathogen predominantly affecting populations in Northern Europe. In immuno-competent individuals, isolated pulmonary disease remains the commonest presentation. The authors report a rare case describing a mycotic popliteal aneurysm caused by M malmoense in a 74-year-old man from Hastings, UK with co-existing pulmonary M malmoense disease. Primary pulmonary disease was confirmed by a combination of history, examination and positive radiological and microbiological findings. Tissue analysis of the aneurysm wall during popliteal aneurysm repair confirmed the presence of disseminated M malmoense. Histological analysis of the aneurysm wall showed non-caseating granulomata. The patient completed a 2 year course of rifampicin, ethambutol and clarithromycin which eradicated the organism from his sputum. Further progress has been complicated by the development of an aspergilloma at the site of his eradicated pulmonary M malmoense disease and the need for angioplasty to his bypass grafts 1 year postsurgery.