Bronchioloalveolar carcinoma and adenocarcinoma with bronchioloalveolar features:: a clinico-pathological spectrum

Bronchioloalveolar carcinoma (BAC) is a pulmonary adenocarcinoma (ADC) developing in the terminal respiratory units. The restrictive definition adopted by the 1999 WHO pathological classification requires a complete resection of the tumour to exclude any evidence of histological invasion. Although IIIB-IV tumours were excluded from the strict WHO definition of BAC, the first international workshop on BAC in 2004 focussed on the need to include in the same disease spectrum both pure BAC and ADC with BAC features (ADC-BAC). BAC and ADC-BAC more frequently affect women, non-smokers and Asians than other non-small cell carcinomas. Their predominantly lepidic airway progression frequently results in a multifocal or diffuse pneumonic presentation and explains why death is more frequently due to bilateral pulmonary involvement than extrathoracic metastases. The natural history is slower and the prognosis better than other ADC. Surgical resection remains the best therapeutic option for localised tumours. The high incidence of epidermal growth factor receptor (EGFR) expression on tumour cells and its gene amplification and/or mutation together with a particular sensitivity of this entity to EGFR tyrosine kinase inhibitors, offer a new strategy of therapeutic management in patients with unresectable tumours. However, the place of chemotherapy has recently been re-evaluated.