Granulomatous Arthritis

Granulomatous Arthritis 

The prototype of granulomatous arthritis is tuberculous arthritis. Atypical mycobacteria, sarcoidosis, and sporotrichosis can cause granulomatous involvement of the synovium, but these entities are much less common.

Synonyms

• Tuberculous arthritis
• Pott disease

Prevalence (In U.S.)

Unknown

Predominant Sex

Male = female

Predominant Age

Rare in childhood

Peak Incidence

No seasonal predilection

Physical Findings & Clinical Presentation

• •Often no constitutional symptoms (fever and weight loss)
• •Possibly no clinical or radiographic evidence of pulmonary tuberculosis (TB)
• •Spinal infection most often in the thoracic or upper lumbar area, with back pain as the most common symptom
• •Considerable local muscle spasm possible
• •Kyphosis and neurologic symptoms resulting from spinal cord compression in advanced disease
• •Chronic monoarticular arthritis in the peripheral joints
• •Single joint involved in 85% of patients
• •Pain, swelling, limitation of motion, and joint stiffness less dramatic than in acute bacterial arthritis; possibly present for months to years
• •Seen more often in persons from developing countries, elderly patients, and hemodialysis patients

What causes Granulomatous Arthritis?

• •Hematogenous spread of organisms from a distant site of infection or by direct spread from bone
• •Most commonly affected area: 50% of cases in the spine; next most commonly affected area: Large joints (knee and hip)
• •Primary infection beginning in the lungs and spreading to the highly vascular synovium
• •Tuberculous osteomyelitis commonly involving an adjacent joint
• •In peripheral joints, a granulomatous reaction in the synovium causing joint effusion and eventual destruction of underlying bone
• •In the spine, infection of the intervertebral disk spreading to adjacent vertebrae
• •Osteomyelitis of vertebrae causing collapse, kyphosis, or gibbous deformity, and possibly paraspinal “cold” abscess

How is Granulomatous Arthritis diagnosed?

Differential Diagnosis

• •Sarcoidosis
• •Fungal arthritis
• •Metastatic cancer
• •Primary or metastatic synovial tumors

Workup

• •High index of suspicion needed
• •Gold standard: Synovial biopsy and culture for bacteria, including acid-fast bacilli, and fungi
• •Joint aspiration and culture of the synovial fluid performed while awaiting biopsy
• •Positive synovial fluid smear for acid-fast bacilli in 20% of cases; positive culture in 80%
• •Elevated synovial fluid protein, low glucose
• •Considerable variation in synovial fluid WBC count, but values of 10,000 to 20,000 cells/mm³ typical; may be predominantly polymorphonuclear leukocytes
• •Usually, a positive tuberculin skin test result implies exposure to TB, not necessarily active disease. Interferon-gamma release assays also can detect exposure to TB but not active disease (QuantiFERON TB Gold Test, TB T-Spot test)
• •Anergy in elderly patients or in advanced disease
• •In spinal infections, percutaneous or open biopsy to obtain accurate C&S data

Laboratory Tests

Peripheral WBC count and ESR are elevated but nonspecific.

Imaging Studies

• •Plain radiographs of the affected joint.
  • 1.Typically demonstrate bony destruction with little new bone formation
  • 2.Osteopenia and soft tissue swelling in early infections
  • 3.Later, erosions at the joint margins
  • 4.In the spine, disk space narrowing with vertebral collapse (wedging) causing characteristic kyphosis
• •CT scan: Useful in early diagnosis of infections of the spine and to detect paraspinal abscess.
• •Technetium and gallium scintigraphic scans: Findings may be positive but do not permit differentiation from inflammation or osteoarthritis.

How is Granulomatous Arthritis treated?

Nonpharmacologic Therapy

Encourage range-of-motion exercises of the affected joint to prevent contractures.

Acute General Treatment

• •Combination chemotherapy
  • 1.If sensitive TB suspected, give isoniazid 5 mg/kg/day (maximum 300 mg/day) plus rifampin 10 mg/kg/day (maximum 600 mg/day) for at least 6 mo and pyrazinamide 15 to 30 mg/kg/day (maximum 2 g/day) for at least the first 2 mo plus ethambutol 15 to 25 mg/kg/day until sensitivity results are available.
  • 2.Most patients are treated successfully with chemotherapy alone.
  • 3.Urgent surgical intervention is necessary if spinal cord compression causes neurologic changes.
• •Surgical debridement in cases of extensive bone involvement

Chronic Treatment

In longstanding extensive disease, arthrodesis of weight-bearing joints

Disposition

Loss of cartilage and destruction of underlying bone if treatment is not initiated promptly

Referral

• •To a physician experienced in the management of TB
• •For consultation with an infectious diseases specialist if drug resistance is suspected or documented
• •For neurosurgical and/or orthopedic consultation if neurologic impairment suspected

Pearls & Considerations

As TB has become less prevalent in the U.S. in the past 10 yr, TB arthritis and osteomyelitis have also become less common. However, because of an increase in patients receiving antitumor necrosis factor-alpha therapy, there has been an increase of granulomatous diseases with nontuberculous mycobacteria such as Mycobacterium avium.

Seek Additional Information

• Hogan J.I., et al.: Mycobacterial musculoskeletal infections. Infect Dis Clin North Am 2017; 31: pp. 369-382.