Evaluation of a new grading system for laryngeal squamous intraepithelial lesions—a proposed unified classification

Abstract

The proposed modification to the Ljubljana classification provides clear morphological criteria for defining the prognostic groups. The criteria facilitate better interobserver agreement than previous systems, and the retrospective follow-up study demonstrates a highly significant difference in the risk of malignant progression between low-grade and high-grade SILs.

Update from the 4th Edition of the World Health Organization Classification of Head and Neck Tumours: What is New in the 2017 WHO Blue Book for Tumours of the Hypopharynx, Larynx, Trachea and Parapharyngeal Space

“…Despite a certain degree of subjectivity, grading precursor lesions in the upper aerodigestive tract remains the most important prognostic factor for the biological behaviour of disease and the leading guidance for clinicians in selecting appropriate treatment. The new WHO 2017 classification is a two-tier system, based on the morphological criteria of the amended Ljubljana classification, which were confirmed to have better inter-observer agreement than had been found in previous studies and with the largest retrospective follow-up study, which presented a highly significant difference in the risk of malignant progression between low-grade SILs and high-grade SILs [6,9]. The morphological criteria of the WHO 2017 classification are reviewed in Table 1 and Fig.…”

“…They were treated more aggressively than patients with high-grade SILs; eight patients were additionally treated with radiotherapy, and one patient with chordectomy. After treatment, all of them were free of disease [9]. Hopefully, further studies of laryngeal dysplasia, classified by the proposed two/three-tier system will bring promising and comparable results of treatment.…”

“…The three classifications of laryngeal dysplasia/squamous intraepithelial neoplasia/SIL presented in WHO 2005, as a result of compromise, have various morphological criteria with different numbers of grades and heterogeneous terminologies. The treatment approaches of cases classified according to these grading systems are not harmonized and their results have proved not to be comparable [6,9,46]. In recent inter-observer studies, in which pathologists used all three classifications, no significant advantage was found for any of the applied grading systems and inter-observer agreements among pathologists were not encouraging [47][48][49].…”

“…Recent study of laryngeal dysplasia confirmed that progression to overt cancer was stable during 20 years at an approximate rate of 8% [51]. The largest published retrospective study, of Table 1 Morphological criteria of the unified two/three tier classification of laryngeal precursor lesions, modified from the amended Ljubljana classification [9] Low-grade dysplasia/SIL (previous categories squamous hyperplasia, mild dysplasia)-low malignant potential-spectrum of morphological changes ranging from squamous hyperplasia to an augmentation of basal/parabasal cells, occupying up to the middle of the epithelial thickness, upper part unchanged Architectural criteria Stratification preserved Transition of basal/augmented parabasal cell layer with perpendicular orientation to the basement membrane to horizontally oriented prickle cell layer in the upper part Spinous layer: spectrum of changes ranging from the whole epithelial thickness up to a variant with prickle cell present only in the upper part Basal/parabasal layer: spectrum of changes ranging from unchanged layer ( 1444 patients with laryngeal SILs, classified according to the amended Ljubljana classification, showed a significant difference (p = 0.0001) in progression to cancer between patients with low-grade and those with high-grade SILs: 19/1204 (1.6%) over a period of 2-15 years and 30/240 (12.5%) over a period of 2-26 years with high-grade SILs. Nine of 49 patients who progressed to cancer were diagnosed as carcinoma in situ.…”

“…The group of CIS is reserved for rare cases with pronounced architectural disorder, severe cellular and nuclear atypias and an increased number of mitoses, including atypical forms. Such a distinction can facilitate clinical decisions about treatment modalities for patients with laryngeal high-grade lesions and CIS [6,9,10].…”