Abstract:Objective To investigate the CT imaging manifestations and clinicopathologic features of patients with primary pulmonary invasive mucinous adenocarcinoma (PIMA) diagnosed pathologically after surgery. Methods The clinical data of 78 patients with PIMA diagnosed pathologically after surgery in the Department of Thoracic Surgery of Anhui Chest Hospital from November 2019 to November 2021 were retrospectively analyzed. Results Among the 78 cases, 33 (42.3%) were male and 45 (57.7%) were female，aged (60.3±7.8) years in total, and serum carcinoembryonic antigen (CEA) was increased (＞5 ng/mL) in 9 cases (11.5%). According to the clinical characteristics, patients could be divided into the asymptomatic group (60 cases, 76.9%) and the symptomatic group (18 cases, 23.1%). The symptomatic group included 8 cases with coughing and coughing up mucus sputum, 4 cases with chest tightness and chest and back pain, and 6 cases with other symptoms. Imaging manifestations showed that 51 (65.4%) lesions were located in the inferior lobes of both lungs and 71 (91.0%) in the peripulmonary,of which 46 patients (59.0%) had completely solid nodules, and common signs included shallow lobulation and vascular cluster sign. Postoperative pathologic stages Ⅰ, Ⅱ, Ⅲa were found in 61 (78.2%), 9 (11.5%) and 8 (10.3%) patients, respectively. Moreover, genetic testing was performed in 13 patients, of which 8 cases were detected with mutations of Kirsten rat sarcoma viral oncogene (KRAS), and 1 case was detected with mutations of epidermal growth factor receptor (EGFR) gene. Twenty-two patients were tested for the expression of programmed death-ligand 1 (PD-L1), and 18 (81.8%) of these patients had a tumor proportional score (TPS) of＜1%. Conclusion Except for expectoration of mucous sputum, PIMA has no specific clinical symptoms. CT manifestations show that the lesions usually occur in the inferior lobes and peripulmonary of the lungs, and most pulmonary nodules are completely solid, which with signs of shallow lobulation and vascular cluster. Laboratory tests show that the expression level of PD-L1 is low, and the KRAS mutations are relatively more frequent. These features have some value in the diagnosis and differential diagnosis of PIMA.