Columnar cell lesions: current classification and controversies.

"Columnar cell lesions" is a general descriptive term referring to disparate lesions having in common cells with a columnar configuration but not necessarily identical histologic or biologic characteristics. Within this large category, a group of lesions having in common a population of atypical cells (frequently columnar shaped) is emerging as early neoplastic lesions. This article reviews the histological features, differential diagnosis, associated lesions, biologic potential, clinical significance, and management of atypical columnar cell lesions.