The mast cell reaction in premalignant and malignant lesions of the head and neck

Abstract

Head and neck squamous cell carcinoma (HNSCC) is one of the most frequent and aggressive neoplasms of this anatomical region. Many studies evaluated the neoplastic cells, but few works focused on the tumor microenvironment. In the present study, we investigated the distribution and mast cell density (MCD) in malignant and premalignant lesions of the oral cavity, tongue, pharynx, and larynx. There were analyzed 52 specimens of HNSCC, and 15 biopsies taken from patients with dysplasia. Results were compared with those found in a control group of 10 biopsies of oral mucosa from patients with inflammatory diseases. Slides stained with Hematoxylin-Eosin were used for the histopathological diagnosis and grade, and mast cells (MCs) were identified by immunohistochemistry, using anti-MC tryptase. MCs were counted using a method similar to that proposed for microvessel density. We found a significant increase in the number of MCs from the normal oral mucosa until overt carcinoma. Unlike normal tissues, in HNSCC, many MCs were found between tumor cells. We found no relationship between MCs and blood vessels in the tumor area. A significant statistical correlation was found between dysplastic and malignant tumors, but not between tumors with a different grade. Also, it was not found relationship between MCD and the anatomical location of the tumor. Based on these results, we believe that MCD evaluated by anti-MC tryptase is an independent factor of prognosis and reflects an unfavorable outcome.

Figure 1

Human gingiva: (A) External control with MCs located in the perivascular space without significant accumulation close to the epithelium – the endothelium of blood vessels was stained with Methyl Green; (B) Moderate dysplasia with accumulation of MCs under the basement membrane; (C) Moderate dysplasia with intraepithelial MCs; (D) Well-differentiated SCC with a relatively low number of MCs; (E) Moderate and less differentiated (F) SCC with a high number of MCs in the tumor area. Anti-MC tryptase antibody immunomarking: (A–F) ×400. MC: Mast cell; SCC: Squamous cell carcinoma.