The Supplementary Diagnostic Power of Selected Immunohistochemical, Molecular Genetic and Infective Parameters in Epithelial Hyperplastic Laryngeal Lesions

Abstract

Objectives: MIB-1 and p53 protein expression, loss of heterozygosity (LOH), microsatellite instability (MSI) of di- and mononucleotide repeats, and HPV status were tested for their potential to characterize different stages of epithelial hyperplastic laryngeal lesions (EHLL). Methods: Thirty-two EHLL were reclassified according to the Ljubljana classification into simple (SH), abnormal (AbH), atypical hyperplasia (AtH) and carcinoma in situ, and investigated by immunohistochemical methods, PCR and direct sequencing analysis. Results: MIB-1 increased with progressive grades of EHLL, whereas p53 protein expression was distinctive only between SH and AbH. LOH showed increasing frequency with grades of the lesions, but the distribution of altered loci (9p, 9q, 10q, 11q, 17p) was not qualified to differentiate between the stages. MSI was detected in SH, AbH and AtH without clear correlation to histopathological grading. HPV infection occurred mostly in SH and AbH (both: 66.7%). Conclusion: MIB-1 labeling and allelic loss could assist histopathological diagnosis in the entire spectrum of EHLL, whereas the MSI results point to a genetic instability of the laryngeal mucosa in general and are therefore not helpful in the distinction of different stages of EHLL. However, future molecular genetic analyses should consider more late events of laryngeal carcinogenesis to improve their diagnostic potential. Furthermore, our results indicate that nonrisky and risky EHLL could probably be caused by different exogenous factors.

Divergent Patterns of Allelic Alterations in Premalignant Laryngeal Lesions Indicate Differences in the Impact of Morphological Grading Characteristics

“…In general, our study revealed a high rate of allelic alterations in loci around 3p21-14 and 9p22-21 without divergent results for the loci which were included in our previous study [12]. The chromosomal arms 3p and 9p have already been found to be early and frequently altered in oral and laryngeal hyperplastic and premalignant lesions of previous studies [8, 17].…”

“…Of those, 27 specimens have been presented in a recent study [12]. The median age at laryngoscopy was 60.5 years (range 44–80).…”

“…Immunohistochemistry, counting of positive cells and determination of MIB-1 expression rate (overall and separately in suprabasal layers of the epithelium) were carried out as described recently [12]. To establish a multiple-step grading system as practiced for atypia and epithelial stratification, we grouped MIB-1 expression according to the following schemes: I/0–14%, II/15–29%, III/30–44%, IV/≥45% for all layers (oMIB-1), and I/0–5%, II/6–11%, III/12–17%, IV/≥18% for the suprabasal layer (sMIB-1).…”

“…To establish a multiple-step grading system as practiced for atypia and epithelial stratification, we grouped MIB-1 expression according to the following schemes: I/0–14%, II/15–29%, III/30–44%, IV/≥45% for all layers (oMIB-1), and I/0–5%, II/6–11%, III/12–17%, IV/≥18% for the suprabasal layer (sMIB-1). Our definition of the upper cut-off level of the first groups (I) in these scoring systems is based on mean values of MIB-1 labeling, which have already been found for normal epithelium as well as simple hyperplasias of the larynx [12, 13]. …”

“…Since our previous study of laryngeal biopsies [12]could not reveal distinctive markers for the characterization of benign and potentially malignant EHLL, we extended the marker panel to 32 microsatellite loci on nine chromosomal arms.…”