From: Sacroiliitis mimics: a case report and review of the literature
Spondylitis & AS | Paget Disease of bone | DISH | Osteitis Condensans Ilii | Sarcoidosis | Brucella & other infections | |
---|---|---|---|---|---|---|
Pelvic Radiographic findings | -Symmetric, bilateral changes (AS) -unilateral changes more common with other spondylitis -primarily inferior (synovial) part of the joint -erosions present -ankylosis at end stage | -iliac wing, iliopectineal and ischiopubic lines: cortical thickening and sclerosis -lytic & sclerotic lesions -mostly asymmetric presentation | -primarily superior (ligamentous) joint area -appearance of “ankylosis” | -triangle of sclerosis in the ilium adjacent to the inferior SI joint -often bilateral -no erosions -normal joint space (no narrowing) | -mostly unilateral, but can be bilateral -sclerosis and irregularities of sacroiliac joints margins -may involve synovial or cartilaginous parts, dependent on if boney or joint granulomatous infiltration | -no Xray changes until about 15 days of infection -extensive erosions -subsequent boney repair (may involve more than the anterior-inferior part) which may progress to ankylosis |
Extra-pelvic radiographic lesions | -continuous spine involvement (no skip lesions) -shiny corner on vertebra bodies involved; squaring of vertebral bodies | -skull and long bones are commonly involved | -Skip lesions in the spine -bulky osteophytic bridging and ossification -“flowing” ALL ossification -all spinal segments, but typically thoracic -extra-spinal entheseal ossification, periarticular hyperostosis of the hands, knees, and elbows and quadriceps tendon | -none | -Often hilar lymphadenopathy, infiltrates on CXR -osseous findings such as reticular “lacy” pattern in phalanges | -Dependent on infectious localization |
Genetic Association | HLA-B27 | HLA-DR2, SQSTM1 gene | Possibly some SNPs in COL6A1 | No HLA association | BTNL2 gene | HLA-B39 (Brucellosis) |
Age at onset, Gender | <40 years old, likely equal sexes | >40 years old | >50 years old | Middle-age, predominantly multiparous females <40 years old | Middle-age | Any age (typically young adults and children) |