Published 3/1/2011

What’s your Diagnosis?

In this feature, AAOS Now publishes a series of images, challenging readers to diagnose the condition depicted. The images for this month’s challenge were submitted by John M. Purvis, MD. He provides the following information:

The patient is a 10- year-old overweight female who has complained of right hip pain for one week. She has no previous history of injury, but has recently taken antibiotics for an ear infection. Examination reveals pain on internal rotation of the hip. Lab results show elevated inflammatory markers (erythrocyte sedimentation rate [ESR] = 85; C-reactive protein [CRP] = 3.8).

What’s your diagnosis? E-mail your decision and rationale to

I 2 Cor Stir FSE.gif
(A) Anteroposterior radiograph of the pelvis; (B) Frog radiograph of the pelvis; (C) Subsequent MRI scan (coronal STIR with fat saturation).

Did you get it right?
Last month, Michael R. Murray, MD, and Michael F. Schafer, MD, from Northwestern University in Chicago provided a series of images and information on a 63-year-old female with lumbar spinal stenosis and degenerative scoliosis who underwent a staged fusion procedure. During the early postoperative period, considerable swelling developed in her bilateral flanks. A CT scan showed a large hematoma involving the bilateral psoas muscles and extending into the retroperitoneal space. The patient was managed conservatively. The remainder of the hospital course was uneventful other than treatment for a urinary tract infection (urine culture was positive for Pseudomonas).

Eight months later, the patient returned to the clinic reporting persistent low-grade fevers and a gradually enlarging and uncomfortable “softball”-sized mass in her right flank. An MRI scan obtained at the time showed a large T2 hyperintense fluid collection located along the anterior margin of the right psoas muscle. There was no communication between the mass and the spinal canal. The patient had a white blood count of 13.6, ESR = 47, CRP = 3.0.

According to Dr. Murray, the patient was diagnosed with an abscess and underwent image-guided aspiration of the fluid; 360 mL of purulent fluid was collected. Pseudomonas was cultured from the aspirate. The patient was treated with aspiration of the fluid followed by a 2-week course of oral levofloxacin.

Do you have a challenging case you’d like to submit for publication? E-mail a short case description and any accompanying images to