Chronic Recurrent Multifocal Osteomyelitis (CRMO)

• Chronic Recurrent Multifocal Osteomyelitis (CRMO) affects predominantly children and adolescents, with a peak age of onset of 10 years and a female preponderance.
• CRMO is characterized by recurrent inflammation at multiple skeletal sites, most commonly involving the tibia, femur, clavicle, foot, or vertebral body and rarely the pelvis or rib cage.
• Associated inflammatory disorders, includes

• → Palmoplantar pustulosis
• → Chronic arthritis
• → Psoriasis
• → Inflammatory bowel disease
• → Pyoderma gangrenosum 
• → Sweet's syndrome, and 
• → Severe acne.

Clinical Features

→ Multiple episodes of localized redness, pain, & swelling of insidious onset & spontaneous regression.

→ Minimal functional impairment during the episodes.

Pathophysiology

• The pathogenesis of this condition remains unexplained.
• Theories include an autoimmune process or an infection from an as yet unrecognized causative agent (such as Mycoplasma, Chlamydia, atypical mycobacterium, or virus).
• Histopathologic examination of lesions may show changes suggestive or diagnostic of osteomyelitis, with numerous neutrophils, bone necrosis, granuloma, and fibrosis with round cell infiltration.

Evaluation

• The diagnosis of CRMO is essentially one of exclusion.

 Diagnostic Criteria includes-

(1) Protracted clinical course of > 3 months' duration

(2) Open biopsy results consistent with chronic inflammation, and 

(3) Failure to identify any infectious organism by culture.

• The initial evaluation of CRMO should include the same laboratory and radiographic studies performed for any suspected infection.

• Microbiologic tests of blood and tissue cultures should not be omitted.
• Plain radiographs of each symptomatic area should be obtained and supplemented by bone scintigraphy, because asymptomatic lesions are occasionally identified in this manner.
  
  

Treatment

• There is No well-defined treatment for CRMO, although most children are treated with NSAIDs and occasionally corticosteroids.
• Effective treatment with interferon gamma has been reported in one case, and it is hoped that this method may help circumvent the prolonged, relapsing nature of CRMO.

Complications

• CRMO is often described as a self-limiting condition of childhood that follows a benign, protracted course without sequelae.
• An early diagnosis can avoid complications associated with unnecessary surgical or antibiotic treatment.