Miliary pattern on chest imaging caused by adenocarcinoma

A 55-year-old, nonsmoking woman without underlying disease presented to the emergency department with a 3-month history of productive cough, dyspnea, night sweats and 4 kg weight loss. On examination, her temperature was 36.8°C, heart rate was 75 beats per minute, blood pressure was 92/73 mmHg, and respiratory rate was 15 breaths per minute. Her peripheral oxygen saturation was 95% on 3 L/min of oxygen. We heard bilateral inspiratory crackles on chest auscultation and did not observe any clubbing of her digits. Her eosinophil count was 7.7% (normal 0%-6%) and her C-reactive protein level was normal. Chest radiography and computed tomography showed a miliary pattern of many small nodules throughout all lung fields. Real-time polymerase chain reaction (RT-PCR) testing for SARS-CoV-2 was negative. Adenocarcinoma with mutations of EGFR is observed in 10%-20% of non-Asian patients with non-small cell lung cancer. It is more frequent in women, nonsmokers or light smokers, and in people of Asian descent.