SYB Case 1 By: Amy

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

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

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

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

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 20-50 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

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

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 www.learningradiology.com

http://www.mypacs.net/cases/OSTEITIS-CONDENSANS-ILII-333821.html

References Tuite, MJ. Sacroiliac joint imaging. Seminars in Musculoskeletal Radiology. 12(1):72-82, 2008 Mar. http://www.radpod.org/2007/09/28/osteitis-condensans-ilii/ www.learningradiology.com http://www.mypacs.net/cases/OSTEITIS-CONDENSANS-ILII-333821.html Nykoliation, JW, et al. Osteitis condensans ilii – a sacroiliac stress phenomenon: A report of a case. Journal of the CCA. 28(1): 209-211, 1984 Mar. Vadivelu, R, et al. An uncommon cause of back pain in pregnancy. Postgrad Med J 2005; 81:65-67. UpToDate