High Intraepithelial Mast Cell Density in Warthin's Tumor

Abstract

Background/aim: Warthin's tumor, the second most frequent neoplasia of the parotid gland, is characterized by a proliferation of both epithelial and lymphoid components. In addition to epithelial and lymphoid cells, various other cell types are implicated to varying degrees in the immune response. Notably, mast cells have long been recognized as a consistent cell population within this tumor. Despite the historical acknowledgment of mast cell presence, their true distribution and significance within Warthin's tumor remain unclear. In this study, we aimed to elucidate the distribution and significance of mast cells in Warthin's tumor.

Materials and methods: Histochemical and immunohistochemical methods were employed for the evaluation of mast cells within tumor specimens.

Results: Our study revealed a notable concentration of mast cells in the epithelial component of Warthin's tumor. Microscopic examination showed predominant lymphoid and epithelial elements with occasional cystic formations. Immunohistochemical analysis identified mast cells in both components, emphasizing their role in the tumor microenvironment. Double immunostaining (mast cell tryptase and CD34) revealed no significant correlation between mast cells and blood vessels. Intraepithelial mast cells (IEMCs) had a significantly higher density in the epithelial component, suggesting a potential association with the tumor's benign nature. The relationship between IEMCs and epithelial cells, especially in the presence of cystic structures, offers valuable insights into the unique features of Warthin's tumor.

Conclusion: Our study contributes to the understanding of mast cells in Warthin's tumor, highlighting a substantial concentration within the epithelial component. This knowledge may pave the way for further investigations into the roles of mast cells in the pathogenesis and treatment of Warthin's tumor.

Keywords: Warthin tumor; immunohistochemistry; mast cell; tryptase.

Figure 1. Intraepithelial mast cells (brown) identified with CD117 staining (A, ×400). Deep epithelial cell layer (brown) intensely positive for CD117 (B, ×200).

Figure 2. Intraepithelial mast cells (red) and small blood vessels (brown) at the epithelium-lymphoid tissue interface. Note the absence of tryptasepositive cells in the lymphoid tissue and the immature nature of the small vessels at the interface (A). High density of intraepithelial mast cells and rare mast cells in the lymphoid component (B). The distribution of mast cells throughout the height of the epithelium, including at the level of the free pseudocystic surface (C). Small cysts with epithelium containing mast cells in the superficial epithelial layer (D). CD34/mast cell tryptase double immunostaining, magnification ×400.