The impact of intracytoplasmic mucin in lung adenocarcinoma with pneumonic radiological presentation.

Objectives: This study investigated the clinical and prognostic impact of intracytoplasmic mucin in lung adenocarcinoma with "pneumonic" radiological presentation, formerly known as bronchioloalveolar carcinoma (BAC).

Patients And Methods: Between 1986 and 2011, clinical and pathological data from 120 consecutive patients with lung adenocarcinoma with "pneumonic" radiological presentation were reviewed. Intracytoplasmic mucin was assessed using a diastase-resistant periodic acid-Schiff staining. The presence of EGFR or K-Ras mutations and ALK rearrangement were determined in surgical samples.

Results: The two predominant histological patterns were invasive mucinous adenocarcinoma (40%) and lepidic predominant adenocarcinoma (32%). Intracytoplasmic mucin was detected in 71 patients (59.2%) who were more likely to be non-smokers (p=0.04) and have bronchorrhea (p=0.006), crepitant rales (p=0.02), or neutrophil alveolitis (p=0.0004). In mucin-producing tumors, EGFR mutation was not detected, K-Ras mutations and ALK rearrangement were present in 32% and 3% of cases, respectively. In non-mucin-producing tumors, EGFR and K-Ras mutations were detected in 17% and 10% of cases, respectively, no ALK rearrangement was detected. In univariate analysis, performance status>0, crepitant rales, bronchorrhea, neutrophil alveolitis, bilateral extension, intracytoplasmic mucin and no surgery were associated with worse survival. In multivariate analyses, intracytoplasmic mucin, neutrophil alveolitis, and no surgery were independent factors for worse survival.

Conclusion: Intracytoplasmic mucin is associated with specific clinical characteristics and is an independent factor for worse survival in lung adenocarcinoma formerly known as BAC.