Correct!
3. The thoracic CT scan is not typical of usual interstitial pneumonitis (UIP)
Although the course of rheumatoid arthritis is variable, the patient does not have changes associated with rheumatoid arthritis on physical examination. He does have a positive rheumatoid factor. Although 50% to 90% of patients with rheumatoid arthritis are rheumatoid factor-positive, the specificity of the test is known to be relatively poor (1). Rheumatoid factor is found in many patients with other autoimmune diseases, infectious diseases and some healthy individuals. Cyclic citrullinated peptide (CCP) antibodies have about a 78% sensitivity for rheumatoid arthritis and positive results have reported in approximately 40% of seronegative RA patients (1).
The pulmonary function testing shows mild obstruction, normal lung volumes but a moderate reduction in diffusing capacity. Advanced UIP would be expected to show restriction on spirometry, reduced lung volumes and reduced diffusing capacity.
The thoracic CT scan was interpreted to show moderate centrilobular and paraseptal emphysema with subpleural reticulation and fibrosis with some associated ground glass opacity. Honeycombing is the hallmark of UIP and refers to clustered cystic air spaces (usually between 3-10 mm in diameter) resembling a beehive honeycomb. UIP is often associated basal reticular changes (2).
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