The insidious and occult characteristics of psoas abscess and clinical features similar to conditions like lumbar strain, abdominal/urologic disorders sometimes cause diagnostic delays; resulting in considerably high morbidity and mortality. Chronic inflammatory conditions of the digestive tract and tuberculosis of spine are the commonest source of secondary abscess in the developed and developing countries, respectively [1].

We report a case of an 86 year with a psoas abscess secondary to mucinous adenocarcinoma of colon.

86 year old female presented with right thigh pain in February 2014. CT scan confirmed the clinical suspicion of right psoas abscess which was drained surgically. Intraoperatively, we found pus mixed with mucinous material coming from a small opening in a rounded structure lateral to psoas which could not be identified. The abscess recurred within 2 days. Culture grew Pseudomonas aerugenosa and streptococcus viridans and histopathology showed metastatsis of mucin secreting adenocarcinoma infiltrating the muscle with pyogenic abscess. Repeat CT scan showed abscess communicating with tumor in the colon(Fig 1). Abscess was drained, but tumor was not addressed considering patients age. The infection resolved with 6 weeks of oral linezolid, however the patient expired after 8 months.

Cultures in secondary psoas abscess are often mixed, with E. coli and Bacteroides spp predominating. One must rule out gastrointestinal/genitourinary pathology in cases where the CT/ USG guided culture reports are suggestive of gram negative infection. The fact that carcinoma of the colon could be a cause of psoas abscess should be considered when an unexplained psoas abscess is diagnosed [2].