Psoas abscess can be primary or secondary1, 2. Primary psoas abscess is usually due to haematogenous spread of infection from an occult source. In the western world, secondary psoas
abscess is usually seen following a gastrointestinal pathology1. Secondary psoas abscess can also be due to genitourinary, musculoskeletal or vascular pathology1, 2.
11% of secondary psoas abscess has been reported to be associated with carcinoma colon3. This condition usually presents with flank or back pain, fever, malaise, weight loss, limping
gait or lump in the groin1, 2. Staph. aureus is the commonest pathogen seen in primary psoas abscess whereas Streptococcus and E. coli are the commonest
organisms associated with secondary psoas abscess1, 2.
CT scan is considered the gold standard2, 4 for diagnosing psoas abscess with a diagnostic rate of 88-100 %4. Though magnetic resonance(MR) images show the exact extent of the
abscess, it has not been widely used as a diagnostic test because of cost and patient comfort implications. Sonography and plain X-Rays are not sensitive imaging modalities for psoas
Psoas abscess can be seen as loss of psoas shadow, abnormal soft tissue shadow, gas inclusions, bony destruction of spine or abscess calcification4 in plain X rays. In sonograms, which
have a diagnostic accuracy of about 60%2, psoas abscess is seen as a hypo-echoic mass or enlarged psoas. In CT scans, it is usually seen as a hypodense mass abutting the psoas muscle.
Management includes appropriate antibiotics and drainage of the abscess. 2In secondary psoas abscesses as in our case, it is wiser to start them on broad spectrum antibiotics before
culture and sensitivity is available. 2Drainage of the abscess may be through CT guided percutaneous drainage or surgical drainage.
Necrotising fasciitis is a soft tissue infection, with usually a polymicrobial etiology. The characteristic feature is gas in the soft tissue. However, this can be inconstant. This in turn leads to
clinical features of crepitus on palpation and the radiologic finding of gas in the soft tissues. Necrotising fasciitis is an uncommon mode of presentation of psoas abscess5. It is
imperative to recognise this complication of psoas abscess as emergency debridement needs to be done in these cases.