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Answers on p 58.
A 58 year schoolteacher was admitted with a two month history of malaise, weight loss, worsening dyspnoea, and dry cough. There was no improvement after a course of antibiotics. There were no symptoms of arthralgia, wheezing, or fever. The patient, a non-smoker, had no history of exposure to animals and no relevant occupational or family history. She was generally in good health, apart from recurrent urinary tract infections.
On clinical examination she was apyrexial, with a respiratory rate of 20 breaths/min and an oxygen saturation of 90% on air. Examination of the cardiovascular, abdominal, and musculoskeletal systems was unremarkable. Chest examination showed decreased expansion and bilateral basal inspiratory crackles on auscultation.
Serum electrolytes, renal function, and urinalysis results were normal. Blood culture was negative. A blood count showed a haemoglobin concentration of 140 g/l and a white cell count of 12.5 × 109/l (neutrophils 84%, eosinophils 0.6%). The erythrocyte sedimentation rate (ESR) was 51 mm/hour. The electrocardiogram was uremarkable, and arterial blood gas measurements while breathing room air were normal. Lung function tests showed a forced expiratory volume in one second of 1.52 litres (55% of predicted) and vital capacity of 1.76 litre (54% of predicted). Flow volume loops were abnormal (fig 1). Imaging investigation included a chest radiograph (fig 2) and a high resolution computed tomography (HRCT) scan of the thorax (fig 3).
(1) What abnormalities are shown in the flow volume loops?
(2) What abnormalities are shown in the chest radiograph and computed tomogram?
(3) What is the differential diagnosis?