Pneumonic-type lung carcinoma with respiratory failure as the first manifestation: A case report and literature review.

RATIONALE: Pneumonic-type lung carcinoma is a rare radiological lung cancer subtype. Its clinical and imaging manifestations are easily confused with pneumonia, leading to frequent misdiagnosis and mistreatment in clinical practice.

PATIENT CONCERNS: A 77-year-old female was admitted with "left-sided body pain for 1 week and head/facial pain for 2 days." Initially lacking typical respiratory symptoms, she developed progressive respiratory failure requiring high-flow oxygen therapy after the initiation of anti-infective treatment.

DIAGNOSES: Chest computed tomography revealed bilateral diffuse consolidation with air bronchograms. Ultrasound-guided percutaneous lung biopsy confirmed the diagnosis of invasive lung adenocarcinoma (non-mucinous). Genetic testing identified an epidermal growth factor receptor exon 19 deletion mutation (p.E746_A750del, variant allele frequency = 41.34%).

INTERVENTIONS: Supportive care, including anti-infectives, expectorants, and high-flow oxygen therapy, was administered upon admission. Following diagnosis, oral targeted therapy with osimertinib was initiated.

OUTCOMES: The patient's dyspnea gradually improved. Chest computed tomography performed 1 week later showed significant absorption of bilateral pulmonary shadows, and the oxygenation indices progressively normalized. Disease remission was sustained during the 2-month follow-up.

LESSONS: This critically ill patient presented with respiratory failure as the initial symptom, creating a high risk for misdiagnosis and mistreatment. Early recognition and definitive diagnosis are crucial for effective treatment. Bedside ultrasound-guided percutaneous biopsy is a viable diagnostic approach for critically ill patients.