A woman with dry cough and breathlessness

A woman in her 40s presented with a 10 day history of breathlessness, fever, a non-productive cough, and myalgia. She had asthma and used a salbutamol inhaler as needed. On assessment, her pulse was 110 beats/min, oxygen saturation 85% on air, respiratory rate 25 breaths/min, and blood pressure 108/76 mm Hg. Widespread crepitations were present on auscultation, but a systemic examination was otherwise unremarkable. Chest x ray identified hilar lymphadenopathy, and her D-dimer level was elevated. Based on suspicion of infection and possible pulmonary embolism, a computed tomography pulmonary angiogram was performed. This showed centrilobular ground glass nodules and focal consolidation with bilateral hilar and mediastinal lymphadenopathy. Pulmonary embolism was excluded.

Table 1 displays laboratory test results. These indicated that the patient had acute anaemia and prompted a request for a blood film (fig 1) and a direct agglutination test.