Studies on Equine Eosinophilic Granuloma and Mast Cell Tumor

This study investigated the morphological and molecular features of equine eosinophilic granuloma (EG) and mast cell tumour (MCT) in 153 horses, analyzing 191 lesions. EG was identified as the most common inflammatory nodular skin disease in horses, characterized by eosinophilic granuloma components (EGC) with mineralized cores and collagen fragments, often involving hair follicles and superficial skin layers. T cells and IL-13 were predominant in EG, suggesting their role in eosinophil recruitment. MCT, a less common neoplastic disease, was primarily located in the deep dermis, with variable EGC presence and large numbers of tumor-associated macrophages (TAMs). IL-5 was the most abundant cytokine in MCT, linked to eosinophil recruitment and survival. The study highlighted distinct histological and cytokine expression differences between EG and MCT, contributing to a better understanding of their pathogenesis.