Acinar adenocarcinoma of the lung is a highly lethal disease.

In Europe, acinar adenocarcinoma may comprise the dominant architectural pattern in as many as 50-60% of all adenocarcinomas.

Acinar adenocarcinoma is a histological subtype of gland-forming cancer that is diagnosed when cuboidal and/or columnar shaped malignant cells in the neoplastic tissue form acini and tubules.

In WHO-2004, BACs are one of four specific histologic subtypes of lung adenocarcinoma, along with acinar adenocarcinoma, papillary adenocarcinoma, and solid adenocarcinoma with mucin production.