CEA Negative Initial Diagnosis of HP Infection Finally Confirmed by Bronchoscopic Biopsy as Lung Adenocarcinoma

Carcinoembryonic antigen (CEA) is a polysaccharide complex that is found in the human respiratory system. It is of significant use in disease surveillance of lung cancer; however, serum CEA can occasionally only offer little assistance. We present a case of recurring infection initially diagnosed as carcinoembryonic antigen-negative in a patient with a history of hypersensitivity pneumonitis infection, which finally led to the diagnosis of lung adenocarcinoma following percutaneous lung puncture.

Appropriate laboratory tests, chest CT, bronchoscopy, percutaneous lung puncture, and pathologic examination were performed to explore the cause of the disease.

Because CEA was negative and a chest CT showed interstitial changes in both lungs with numerous hyperdense shadows, coupled with the patient's history of hypersensitivity pneumonitis, we initially believed that the infection was relapsing. However, a percutaneous lung puncture eventually revealed that the patient had lung adenocarcinoma.

Vigilance needs to be increased in clinical work for patients with interstitial lung disease, low tumor markers such as CEA, and imaging suggestive of inflammatory progression, which in fact turns into lung cancer. When the treatment is ineffective after standardized application of hormone and anti-infection, lung tissue should be obtained for pathological examination in time to obtain pathological evidence.