Clinical applicability of the Ljubljana classification of epithelial hyperplastic laryngeal lesions

The diagnosis, prognosis, and choice of treatment of various laryngeal lesions depends almost entirely on the interpretation of changes in the covering epithelium. These abnormalities, referred to as epithelial hyperplastic laryngeal lesions, have been graded according to the Ljubljana classification into simple, abnormal and atypical (risky epithelium) hyperplasia and carcinoma in situ. The aim of this study was to evaluate the clinical applicability and prognostic value of this classification and to determine the incidence of malignant transformation. A retrospective clinical-pathological analysis was performed in a series of 4167 patients with 4574 biopsies, treated from 1979 to 1994. Simple (benign prickle cell) hyperplasia was the predominant grade in nodules, polyps, Reinke's oedema, granulomas, and papillomas, accounting for 37.6-68.6% of cases. In chronic laryngitis, abnormal (benign basal cell) hyperplasia was predominant with 43.9% of cases. Atypical ('risky') hyperplasia was observed almost exclusively in patients with chronic laryngitis (16.1%) and papillomas (10.1%), and only exceptionally in patients with vocal cord nodules (0.9%) and Reinke's oedema (0.3%). The percentage of malignant transformation in atypical hyperplasia was 11.6% (13/112 patients in 2-12 years), while in simple and abnormal hyperplasia, it was 0.3% (8/2920 patients in 1.5-11 years). The data support the concept of the Ljubljana classification dividing epithelial hyperplastic laryngeal lesions into benign (simple and abnormal hyperplasia), potentially malignant (atypical hyperplasia) lesions and carcinoma in situ.