Abstract: Objective: To investigate the clinical characteristics and diagnosis and treatment process of a patient with invasive mucinous adenocarcinoma (IMAs)of lung,and to improve the clinician's understanding of IMAs. Methods: The general materials, imaging manifestations and treatment plan of a patient with IMAs were collected, and the related literature review was conducted. Results: A 42-year-old female patient was admitted to hospital due to cough and expectoration, the CT examination results showed the bilateral lung patchy shadows, the patient was suspected of having pneumonia.After anti-infective treatment, the patient's symptoms did not improve. The pathological findings of transbronchial lung biopsy(TBLB) and the examination of exfoliated cells of pleural fluid all showed inflammation, and the pathological result of percutaneous biopsy was IMAs. The result of gene detection was 2-point mutation in exon of KRAS. After chemotherapy with paclitaxel plus carboplatin combined with bevacizumab, the symptoms of the patients were improved significantly, and the changes of imaging manifestations were obvious. Conclusion: IMAs is a special pathological type of lung adenocarcinomas (ADCs) with various imaging manifestations and specific gene expression. The treatment principles are different from those of the other types of ADCs.

Key words: invasive mucinous adenocarcinoma of lung, lung adenocarcinomas, gene mutation, imaging manifestation