Micropapillary-Predominant Invasive Adenocarcinoma with Aerogenous Spread-A Case Report

Micropapillary components of lung adenocarcinoma are classified into 2 types, aerogenous and stromal invasive, based on their pattern of dissemination. Aerogenous spread is characterized by the presence of tumor cells floating within the alveolar spaces rather than invading the stroma, and is more frequently encountered than the stromal invasive type. This suggests that metastasis of tumor cells occurs via the alveolar spaces by intercellular and cell-matrix interactions, and involves a neutrophil-mediated process and subsequent signaling cascades. The clinical presentation includes multifocal intrapulmonary metastases, the shedding of tumor cells that are found in the bronchoalveolar lavage, and an inflammatory process in the non-neoplastic lung tissue. Aerogenous spread therefore indicates a rather poor prognosis. We presented a 68-year-old woman with T4N0M1a adenocarcinoma and multifocal intrapulmonary metastases. The pathological examination of resected tissue showed micropapillary-predominant invasive adenocarcinoma with an aerogenous spread within the alveolar space. The non-neoplastic lung tissue showed marked inflammation and necrosis.