Case if the Month #10, Answer

Kudos to dzeccola for an accurate, succinct, and incredibly prompt answer to this clinical conundrum.

To review: We have a 49 year old man with pain on/inability to flex the right hip with concomitant fever and weight loss.

What is your next diagnostic step?

Dzeccola is correct – This case is concerning for a psoas abscess, which can be diagnosed by a CT scan of the abdomen/pelvis with IV contrast. Our imaginary patient’s CT scan may have looked like this:

You can see a large, loculated mass overlying the R psoas muscle extending up, and possibly originating from, the R renal pelvis.

Treatment?

Antibiotics and surgery consult – though more frequently these are treated by IR drainage.

Pathophysiology?

The infection can be hematogenous (primary) versus contiguous spread (secondary, from GI, msk, or GU sources).

Risk factors include IV drug use (more likely primary/hematogenous), HIV, DM, Renal failure, other sources of immunosuppression.

Staph is the usual causative organism identified in about 80% of case. Other causative organisms that need to be considered are Psuedomonas, Serratia, Proteus, Haemophilus, enterics. Special considerations for TB/syphilis.

Common presenting symptoms?

Insidious onset – May present several times, may seek treatment through primary care before being see in the ED

Typically, hip, back, or abdominal pain, usually presenting with some systemic symptoms such as malaise, subjective fever, weight loss, night sweats

By Dr. Andrew Kopping and Dr. Andrew Grock

References:

Tintinalli’s Emergency Medicine Chpt 278 “Hip and Knee pain”

Medscape “Psoas Abscess: A Primer for the Internist” http://www.medscape.com/viewarticle/410693

UpTo Date “Psoas Abscess” http://www.uptodate.com/contents/psoas-abscess