Osteoarthritis
Epidemiology and Etiology:
- Heterogeneous group of conditions
- Most common joint disease after 65 years (60% of
men, 70% of women)
- Multifactorial etiology
- Inflammatory
- Chronic inflammatory arthritis
- Metabolic
- Mechanical
- Trauma
- Repetitive joint use
- Congenital malformations
- DDx:
- Avascular necrosis
- Rheumatoid arthritis
- Pseudogout
- Pigmented villonodular
synovitis
Common sites:
Gross features:
- Disruption of the articular cartilage
- Thinning
- Disruption
- Fibrillation
- Exposed bone
- Dense, polished appearance like marble
(eburnation)
- Sclerotic thickened bony trabeculae maybe
- Cysts with fluid and fibromyxoid
tissue maybe
- Superficial bony necrosis maybe
- Papillary masses of metaplastic cartilage, bone,
or adipose tissue maybe
Histologic features:
- Disruption of the articular cartilage is the fundamental
finding
- Vertical clefts in the cartilage are
characteristic
- Villous hyperplasia maybe
- Mild chronic inflammation of the synovium maybe
- Papillary masses of metaplastic cartilage, bone,
or adipose tissue maybe
- Bone findings:
- Sclerotic thickened bony trabeculae maybe
- Cysts with fluid and fibromyxoid
tissue maybe
- Superficial bony necrosis maybe
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Immunophenotype:
Marker:
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Sensitivity:
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Specificity:
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Molecular features:
Other features:
References:
- The Washington Manual of Surgical Pathology, 2nd
ed. (2012)