Invasive mucinous adenocarcinoma of the lung was previously known as mucinous bronchioloalveolar carcinoma. It consists of goblet cells or columnar cells with abundant intracellular mucin usually arranged in a lepidic pattern along the alveolar septa. The tumor foci may be patchy in distribution (as seen here) or confluent. All other patterns, except solid pattern, such as papillary, micropapillary, and acinar may also be seen. Invasive mucinous adenocarcinomas have a greater tendency than other lung adenocarcinomas to be multicentric, multilobar, and bilateral.