The purpose of the present study was to evaluate mast cell density in squamous cell carcinoma tissues of dogs and cats to assess species differences. Skin squamous cell carcinoma tissues from dogs (n = 15: n = 10 from body sites and n = 5 nail bed specimens) and cats (n = 15, n = 10 from ears and n = 5 nasal planum specimens) were examined. Intratumoral mast cell density (IMCD), peritumoral mast cell density (PMCD) and total mast cells density (TMCD) as a sum of IMCD and PMCD were calculated from Giemsa-stained slides at high magnification in 1 mm² using an Olympus microscope (Olympus BX41, Tokyo, Japan) equipped with a digital Olympus DP72 image camera and CellSensDimension software V1.16). Both intratumoral and peritumoral tissues of the squa.mous cell carcinoma were divided into two categories: (1) loose, well-vascularized, rich in lymphocytes and plasmocytes, macrophages and neutrophils; and (2) fibrous, with few or no lymphocytes, plasmocytes, macrophages and neutrophils (the presence of neutrophils can be associated with actinic keratosis, mechanical irritation of the tumor in some anatomical areas during scratching with teeth, but, in general, neutrophils are associated with more invasive squamous cell carcinoma). In cats, a markedly higher total number of mast cells was found, and the number was also higher in intratumoral and peritumoral tissues. A similar tendency was found in both dogs and cats—a markedly higher number of mastocytes was found in both peritumoral and intratumoral loose, well-vascularized connective tissue. Conversely, lower numbers of mast cells were found in both intratumoral and peritumoral compact fibrous tissue in both animal species.

Although oral leukoplakia (OL) is recognized as a precancerous lesion, only a proportion of cases undergo malignant transformation (7,2 % to 9.5%). That's why recently, increasing attention has been directed toward molecular biomarkers that may better reflect the biological behaviour of OL Infiltration density of T and B lymphocytes, macrophages, plasma cells were assessed semi-quantitatively using a 4-point scale adapted from Nankivel study. CD9 antigen was assessed in epithelial and immune cells by counting them in three 400x fields. CD138 and CD68 biomarkers were associated with significantly elevated expression across both clinical types of OL where dysplasia was diagnosed. The increase in infiltration density with CD3 and CD20 labelled lymphocytes was statistically reliably confirmed only in non-homogeneous OL with dysplasia. CD9, as a protein reflecting the exosome compartments, revealed the interaction between the epithelium and immune cells. A moderate, statistically significant positive correlation was found only in leukoplakia with dysplasia between CD9+ immune cell levels and the number of epithelial layers expressing this antigen. Assessment of combinations of CD3, CD9, CD20, CD68, and CD138 biomarker expression, cons idering clinical type of leukoplakia, particularly non-homogeneous, appears to improve the accuracy of determining the risk of malignancy in individuals with oral dysplasia.

Oral leukoplakia (OL) is a potentially malignant lesion, but only a proportion of cases undergo transformation to carcinoma (7.2% to 9.5%). The aim of this study was to analyze the possible differences and the role of immune cells in homogeneous and non-homogeneous OL at different grades of dysplasia. The infiltration density of T and B lymphocytes, macrophages, plasma cells, and cells expressing CD9 antigen was assessed semi-quantitatively in 50 OL cases using a 4-point scale—score 1 (<5%), score 2 (6–10%), score 3 (11–15%) and score 4 (16–20%)—via manual counting by two morphologists. Both clinical types of OL that showed dysplasia had noticeably higher proportions of CD138+ and CD68+ immune cells. Statistical analysis confirmed that only non-homogeneous OL with dysplasia showed an increase in the infiltration density of CD3+ and CD20+ lymphocytes. There was a statistically significant moderate positive correlation between the amount of CD9+ cells in the lamina propria and the number of labeled epithelial layers in OL of different thicknesses. Expression of CD138 and CD9 proteins in epithelial and connective tissue cells in OL indicates active epithelial–mesenchymal interaction during the premalignant stage of OL, but the expression of these markers in epithelial and immune cells was completely the opposite. The evaluation of CD3, CD20, CD9, CD138, and CD68 antigen expression, particularly in non-homogeneous leukoplakia, improves the accuracy of malignancy risk assessment in patients with dysplasia.