A 57-year-old woman presents with worsening exertional dyspnea for 1 year, along with a non-productive cough, fatigue, and small-joint arthralgia. She has no other symptoms. Her medical, drug and family histories are unremarkable. She has never smoked and has no history of exposure to organic or inorganic dusts or environmental allergens. A full blood count is normal. C-reactive protein levels are normal, but ESR is 50 mm/1h.