Rheumatoid pulmonary nodule

Rheumatoid pulmonary nodules are a rare pulmonary manifestation of rheumatoid arthritis. They are thought to occur in <1% of patients with rheumatoid arthritis.

Epidemiology

They occur more often in men than in women and usually are seen in smokers with subcutaneous nodules and high rheumatoid factor titers. 

Clinical presentation

Many patients can be asymptomatic. Rheumatoid pulmonary nodules can arise before rheumatoid arthritis is manifested clinically or may develop concurrently. 

Pathology

On histology, they appear identical to the nodules found in subcutaneous tissue. Necrobiotic nodules also can occur in lung before clinical arthritis develops or even the absence of rheumatoid factor

Location

Rheumatoid nodules tend to be located in the periphery of the upper and middle zones. 

Radiographic features

Plain radiograph

Not very sensitive (may only be detected a very small proportion of cases on plain film) ⁵.

CT

On HRCT or CT of the chest: 

• nodules can be quite variable in appearance ⁵
  • associated cavitation may be seen
• may be single or multiple
• size ranges from 0.5-7 cm ^3,5
• rarely these nodules can have associated calcification
• tend to be peripheral, subpleural or pleural ⁸

Nuclear medicine

Rheumatoid nodules may demonstrate FDG-18F avidity on PET-CT. ⁷

Treatment and prognosis

Their natural history follows an unpredictable course. These nodules may undergo cavitation, increase in size, or resolve spontaneously over time. Their course often has no relationship to the course of the rheumatoid arthritis.

Complications

• rupture into the pleural space (rare): with resultant pneumothorax, pleural effusion, or empyema