CASE 45

By: Dr. Mai Mattar, MD & Dr. Nizar Al-Nakshabandi MD, FRCPC

HISTORY: 25-year-old female with long standing backpain.

What are your findings?

What is the differential diagnosis?

What are the causes?

FINDINGS:

Axial T1 and T2FS (A and B), coronal T1 and T2FS (D and E) a bone window of a pelvic CT (C) demonstrate bilateral erosive changes involving the iliac and sacral counterparts of the joints along with marrow edema. On CT, sclerotic changes are appreciated.

DIFFERENTIAL DIAGNOSIS:

Inflammatory sacroiliitis, infective sacroiliitis, lumbar disc disease.

DIAGNOSIS:

Bilateral grade III inflammatory sacroiliitis.

PEARLS AND DISCUSSION:

Differential diagnosis of bilateral and symmetrical sacroiliitis is: Enteropathic arthritis associated with Crohn’s disease or ulcerative colitis and rarely Whipple’s disease, ankylosing spondylitis, rheumatoid arthritis, hyperparathyroidism: [Pseudo-sacroiliitis].

Mnemonic

• P: Psoriatic arthritis.

• A: Ankylosing spondylitis.

• I: Inflammatory bowel related.

• R: Reactive (e.g. Reiter syndrome).

Sacroiliitis grading can be achieved using plain radiographs according to the modified New York criteria 4.

• grade 0: normal.

• grade I: some blurring of the joint margins – suspicious.

• grade II: minimal sclerosis with some erosion.

• grade III

  • definite sclerosis on both sides of joint.

  • severe erosions with widening of joint space with or without ankyloses.

• grade IV: complete ankyloses.

FURTHER READING:

1. Brower AC, Flemming DJ. 2012. Arthritis in Black and White. 3rd edition. Philadelphia, PA. Elsevier.

2. Weissleder R, Wittenberg J, Harisinghani MG. Primer of diagnostic imaging. Mosby Inc. (2003) ISBN:0323023282.