Pneumococcal psoas abscess.

Primary extrapulmonary pneumococcal disease has become a rarity in modern times. We describe a 40-year-old patient who developed an abscess of the psoas muscle as the only evidence of pneumococcal disease. A predisposing local condition was prior trauma of the psoas muscle, documented by the existence of myositis ossificans circumscripta. This case emphasizes the importance of considering unusual sites of involvement of pneumococcal disease.