Which of the following is NOT true about Bronchoalveolar carcinoma?

Ans. b (Stromal invasion with desmoplasia) (Ref. Robbins 7th/76l)By definition, bronchioalveolar ca do not demonstrate destruction of alveolar architecture or stromal invasion with desmoplasia, features that would merit their classification as frank adenocarcinomas.BRONCHIOLOALVEOLAR CARCINOMAS (BACS)# Included as a subtype of adenocarcinomas in the current WHO classification of lung tumors.# Involve peripheral parts of the lung, either as a single nodule or, more often, as multiple diffuse nodules that may coalesce to produce pneumonia-like consolidation.# The key feature of BACs is their growth along preexisting structures and preservation of alveolar architecture.# The tumor cells grow in a monolayer on top of the alveolar septa, which serves as a scaffold (this has been termed a "lepidic" growth pattern, an allusion to the neoplastic cells resembling butterflies sitting on a fence).# The two subtypes of BACs are:- Mucinous (comprising tall, columnar cells with prominent cytoplasmic and intra-alveolar mucin) and- Non-mucinous# The "cell of origin" for peripheral adenocarcinomas have now identified a population of multipotent cells at the bronchioalveolar duct junction, termed bronchioalveolar stem cells (BASCs).