26th February 2025

A 65-year-old woman with non-small cell lung cancer is being treated with a combination of chemotherapy and immunotherapy

A 65-year-old woman with non-small cell lung cancer is being treated with a combination of chemotherapy and immunotherapy with pemetrexed and pembrolizumab. She has a right upper lobe mass with metastases to her mediastinal nodes. She had a re-staging scan 2 weeks ago that demonstrated very good treatment response, with radiological improvement at all sites of her disease.

She presents to the emergency department with a 3-day history of breathlessness and a dry cough.

Her observations are as follows: heart rate 92 bpm, blood pressure 132/78 mmHg, respiratory rate 26, oxygen saturation 84% on room air, temperature 36.4 degrees.

Her admission bloods show: Hb 123 g/L (115-165 g/L), haematocrit 0.41 l/L (0.34-0.46 l/L), MCV 86 fLl (80-100 fL), WCC 5.6 x 10⁹/L (4.0-11.0 x 10⁹/L), neutrophils 2.7 x 10⁹/L (2.0-7.5 x 10⁹/L), lymphocytes 2.4 x 10⁹/L (1.5-4.5 x 10⁹/L), platelet count 296 x 10⁹/L (150-450 x 10⁹/L), Na 141 mmol/L (133-146 mmol/L), K 4.8 mmol/L (3.5-5.3 mmol/L), creatinine 96 µmol/L (45-104 µmol/L), urea 5.2 mmol (2.5-7.8 mmol/L), CRP 12 mg/L (<5 mg/L).

High-resolution CT chest reveals bilateral widespread ground-glass change throughout both lungs.  She is started on oxygen therapy via face mask and her oxygen saturations improve to 96%.

What is the most likely diagnosis?

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