Capnocytophaga sputigena primary iliopsoas abscess.

Iliopsoas abscess is usually secondary to the spread of infection from a contiguous focus. Primary disease is uncommon, except in children where Staphylococcus aureus is the main pathogen. We report a 60-year-old woman who developed a primary iliopsoas abscess as a result of haematogenous spread of Capnocytophaga sputigena from a palatal fistula and chronic sinusitis due to previous treatment for nasopharyngeal carcinoma. Pyomyositis due to unusual and fastidious Gram-negative bacilli should be considered in patients with head and neck tumours who have previously received radiotherapy.