Abstract:

On April 17, 2019, a 69-year-old male patient with pulmonary lymphangitic carcinomatosis was admitted to the Respiratory Department of Wuhan Pulmonary Hospital,and diagnosed as pulmonary tuberculosis due to the positive tuberculosis molecular biological result in other hospital. The patient was hospitalized because of “pulmonary shadow for 3 months and intermittent cough for 2 months”. He had previously been diagnosed with colon cancer. Chest CT scan revealed diffusing nodules along bronchovascular bundles with ground glass shadows, interlobular septal thickening, bilateral hilar and mediastinal lymph node enlargement and bilateral pleural effusion. In bronchoalveolar lavage fluid (BALF), MTB (extremely low) was detected by GeneXpert MTB/RIF (referred to as “GeneXpert”) and MTB was detected by TB-PCR in previous hospital. Therefore, he was diagnosed as tuberculosis, then transferred to Wuhan Pulmonary Hospital. After admission, relevant examinations were completed. PPD skin test and interferon gamma release test was negative, and chest CT imaging features were not consistent with pulmonary tuberculosis. We suspected it was a false positive molecular biological result. Therefore, GeneXpert and tracheal endoscopic ultrasound-guided needle aspiration biopsy (EBUS-TBNA) were recommended. However, the patient refused. The doctor performed a pleural puncture for diagnosis, and 20 ml pleural effusion was extracted. The examination showed that the carcinoembryonic antigen (118.4 μg/L) was significantly elevated, indicating malignant pleural effusion. Finally, medical thoracoscopic pleural biopsy revealed metastatic poorly differentiated adenocarcinoma. Combined with chest CT findings, the patient was diagnosed as pulmonary lymphangitic carcinomatosis who later died due to deterioration of his condition. Therefore, the authors suggest that radiographic findings of nodules along the bronchovascular bundle with thickening of interlobular septa and mediastinal lymph node enlargement should be considered as pulmonary lymphangitic carcinomatosis for differential diagnosis. When imaging findings are not consistent with tuberculosis and molecular biological test is positive, we should be cautious about diagnosing tuberculosis to avoid misdiagnosis and mistreatment.

Key words: Tuberculosis, Pulmonary lymphangitic carcinomatosis, Molecular biology, Diagnosis