Osteomyelitis

Epidemiology and Etiology:

· Inflammation of the bone and marrow

· Infectious

· Pyogenic bacteria (pyogenic osteomyelitis)

· Staph. Aureus (80-90%)

· Group B strep (neonatal)

· Mycobacteria

· Other bacteria

· E. coli

· Pseudomonas

· Klebsiella

· Haemophilus influenzae

· Viruses

· Parasites

· Fungi

· No organisms isolated (50%)

· Hematogenous spread

· Trauma of affected bone predisposes

· Initiating primary infection may be occult or very transient

· Direct extension

· Complex fracture

· Surgery

· Non-infectious:

· Chronic recurrent multifocal osteomyelitis (CRMO)

Common sites:

· Long bones (metaphysis, epiphysis)

· Vertebral bodies

Gross features:

· Frequently manifests as a primary solitary focus of disease

Histologic features:

· Fibrosis

· Reactive bone deposition

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

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Other features:

· Chronic osteomyelitis (5-25%)

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References:

· Kumar V, Fausto N, Abbas A. Robbins & Cotran Pathologic Basis of Disease, Seventh Edition. 7th ed. Saunders; 2004.