Pulmonary preneoplasia.

CONTEXT: Improved screening techniques for lung cancer have resulted in detection of lesions that are considered to represent precursors of invasive lung carcinomas. These lesions may cause a diagnostic dilemma particularly on small biopsy or cytology specimens. Ancillary studies are usually not helpful, and diagnosis is based on morphology alone. Recognition of these lesions is very important to prevent potential diagnostic mistakes that may result in inadequate patient management. Future molecular studies may provide clinically useful diagnostic and prognostic gene markers.
OBJECTIVE: To review currently proposed morphologic criteria for precursor lesions of non-small cell lung carcinomas including squamous dysplasias, atypical adenomatous hyperplasia, and diffuse idiopathic neuroendocrine cell hyperplasia. Major molecular abnormalities are briefly discussed. DATA SOURCES: Published literature and recent World Health Organization classification of lung tumors.
CONCLUSIONS: Practicing surgical pathologists must be familiar with morphology of recognized pulmonary preneoplastic lesions that are more frequently detected radiographically and subjected to diagnostic procedures. Future understanding of underlying molecular abnormalities associated with progression of these lesions into invasive lung carcinoma may result in a development of molecular assays with potential diagnostic and prognostic importance.