Prognostic Significance of Skin Eosinophil Counts in Bullous Pemphigoid

Bullous pemphigoid is the most common vesiculobullous autoimmune disease, and clinically, peripheral eosinophilia is observed in half of the patients. This study aimed to analyze the relationship between tissue eosinophil count and peripheral eosinophilia, mucosal involvement, disease severity, and treatment response. Skin biopsies from seventy-seven patients diagnosed with bullous pemphigoid were re-evaluated. Patients were classified according to tissue eosinophil count as having low (1–20 eosinophils/HPF) or high (>20 eosinophils/HPF) eosinophil counts. Additional data, such as peripheral blood eosinophil count and treatment response, were also recorded. The mean age of the patients was 75.08 years (range: 36–95), and 51.9% were female. Tissue eosinophil counts ranged from 1 to 167, with a mean of 28.79. Peripheral eosinophilia was detected in 39% of the patients. A significant correlation was found between peripheral eosinophilia and tissue eosinophil count (p<0.001). The high peripheral eosinophilia group had significantly more extensive disease (p=0.034), and patients with peripheral eosinophilia had a higher rate of complete remission (p=0.027). No significant association was found between tissue eosinophil count and ESR, CRP, mucosal involvement, lesion severity, or treatment response. Tissue eosinophil count and peripheral eosinophilia are closely related. While peripheral eosinophilia was associated with disease severity and treatment response, tissue eosinophil count was not correlated with clinical features. Different results have been reported in the literature. High comorbidity and advanced age, combined with difficulties in disease control and lack of standardized treatment protocols, are believed to contribute to the variability observed across studies.