1. SYB Case 1
By: Amy

2. History 37 y/o female Chronic diarrhea/steatorrhea
Worsened after the birth of her second child in January of 2006
Previously had a colonoscopy and endoscopy, which were negative
Negative stool studies
Small bowel follow through with thin barium

8. Diagnosis
There is filling of the stomach and small bowel to the terminal ileum and into the large bowel. There are no strictures. There is no thickening of the mucosa. There is no cobblestoning
Normal small bowel series
The scout abdominal radiograph and the single image of the left sacroiliac joint demonstrate an incidental finding of increased density of the left ileum adjacent to the sacroiliac joint
Incidental note is made of left osteitis condensans ilii

10. DDx Ankylosing spondylitis
Chronic inflammatory disease of the axial skeleton manifested by back pain and progressive stiffness of the spine
Characteristically affects young adults with a peak age of onset between 20 and 30 years
Often presents with sacroiliitis, which appears as erosions, sclerosis, and joint space narrowing, eventually leading to ankylosis
May cause erosions and osteitis at the ischial tuberosities, iliac crest, symphysis pubis, and femoral trochanter
Early sign of spinal involvement is squaring of the vertebral bodies due to anterior and posterior spondylitis (“bamboo spine”)
Several disorders can cause sacroiliitis-like changes of the joint, including hyperparathyroidism and repetitive shear-stress injuries in athletes
Paget’s disease

11. Ankylosis of the sacroiliac joint in advanced ankylosing spondylitis with complete obliteration of the joint space
UpToDate

12. Osteitis Condensans Ilii
Believed to develop in approx 2% of adults
Virtually all patients are mutiparous females, but it can occur in men
Age of incidence is between years, with a mean age of approx 35 years
Benign sclerosis of the iliac side of the sacroiliac joints
The sclerosis appears triangular with the base located inferiorly
Erosions of the SI joint are absent
Unlike ankylosing spondylitis, the articular margins of the sacroiliac joint are intact and the joint space is preserved in OCI and the sclerosis involves only the iliac side of the joint
The outer margin of the sclerosis is usually well defined
Usually bilaterally symmetric, but can be unilateral
May spontaneously resolve
Often found incidentally on X-rays of the pelvis or lower back
Rarely symptomatic, but may be mildly painful
May also have morning stiffness and polyarthralgia

13. Osteitis Condensans Ilii
Theories:
Stress-related sclerotic reaction in the peri-articular bone caused by remodeling of bone following stress across the sacroiliac joint (and possibly also the increased vascularity during pregnancy)
Also may be related to loosening of the pelvic ligaments and increased stress on the SI joints during pregnancy and childbirth
Related to a urinary tract infection
Related to a form of inflammatory arthritis
If the dx is in doubt, obliquie views of the SI joints will show that the joint is intact

14. Sclerosis of the ileum adjacent to the sacroiliac joint
Typically bilateral, symmetrical, and triangular in shape
SI joint is normal with no irregularity, erosions or loss of joint space

16. References
Tuite, MJ. Sacroiliac joint imaging. Seminars in Musculoskeletal Radiology. 12(1):72-82, 2008 Mar.
Nykoliation, JW, et al. Osteitis condensans ilii – a sacroiliac stress phenomenon: A report of a case. Journal of the CCA. 28(1): , 1984 Mar.
Vadivelu, R, et al. An uncommon cause of back pain in pregnancy. Postgrad Med J 2005; 81:65-67.
UpToDate