How would you approach the evaluation and management of a patient with rheumatoid arthritis receiving leflunomide who presents with progressive peripheral pulmonary cavitary nodules, with biopsy revealing necrotizing granulomatous inflammation?

Given the association between leflunomide and nodules with necrosis and giant cells (though quite rare), I would consider stopping leflunomide and moving to another agent. I would, of course, make sure that cultures are negative on those nodules, given it could be mycobacterial, fungal, or even GPA.

A couple of things to keep in mind when considering infections here!

• 1st is that slow-growing mycobacteria (including TB) often take 6 weeks to culture, and AFB smears/stains have low sensitivity. BAL Culture has high sensitivity.
• 2nd is that fungal organisms, actinomyces, and nocardia have low cul...