An unusual cause of breathlessness

A 68 year old woman was referred by her general practitioner with a history of exertional breathlessness over the past 10 years. Her symptoms had become more noticeable over the previous few months, especially when walking up inclines and climbing stairs. Echocardiography had shown good biventricular function and no evidence of valvular disease. Chest radiography was not performed at this time. She had been investigated for ischaemic heart disease in the past, and coronary angiography had excluded OK atherosclerotic disease.

Basic spirometry was within normal limits and a flow-volume loop was not performed.

Her medical history included hypertension, for which she was prescribed a calcium channel blocker. She had never smoked and drank alcohol very occasionally.

On examination she appeared well and was not dyspnoeic at rest. Her blood pressure was slightly raised at 145/90 mm Hg and her pulse was 80 beats/min in sinus rhythm. Cardiovascular examination was normal and auscultation of her chest identified bilateral late inspiratory basal crepitations.

Routine biochemical and haematological blood test results were normal. Thyroid stimulating hormone was slightly raised at 5.6 mIU/L (normal range 0.27-4.2) and free thyroxine 15.8 pmol/L (normal range 12.0-22.0; 1 pmol/L=0.08 ng/dL).

She underwent chest radiography …