Diagnosis, clinicopathological characteristics and prognosis of pulmonary mucinous adenocarcinoma

Primary pulmonary mucinous adenocarcinoma (PPMA) is an uncommon subtype of lung adenocarcinoma. The present study attempted to clarify the diagnosis, clinicopathological characteristics, and pathologic significance of epithelial growth factor receptor (EGFR) and Kirsten rat sarcoma viral oncogene (KRAS) mutations and the prognosis of PPMA. A total of 29 patients with PPMA from among 1,469 surgically resected patients with lung adenocarcinoma were enrolled. All of the tumours expressed CK7 and 5 cases exhibited co-expression with CK20. A total of 8 cases expressed EGFR, 14 cases expressed P53 and 2 cases expressed CEA. The majority of mucinous adenocarcinomas expressed thyroid transcription factor 1, Napsin A, Villin and Cam5.2 proteins. KRAS mutations were observed in 62% of patients and were more prevalent in the lower lung lobe and in patients with invasive mucinous adenocarcinoma. A total of 2 cases exhibited an EGFR mutation, and the co-mutation of KRAS and EGFR was only detected in 1 case. The relapse-free and overall survival rates at 5 years were 70.4, and 81.5%, respectively. The results may assist to identify a molecular target and supply important information for a therapeutic strategy for patients with PPMA.