Eosinophilia in BP

Summary Bullous pemphigoid (BP) is a skin condition that causes rashes and itchy blistering in the skin. 50‐60% of BP patients are also reported to have peripheral eosinophilia (PE), a painful disease caused by increased levels of disease‐fighting white blood cells called eosinophils. The objectives of this study, from Israel, were to learn more about which BP patients are affected by PE and to study the relationship between above‐average eosinophil levels in the blood (known as serum eosinophilia) and the symptoms of BP. To do this, 225 BP patients and 1125 control participants (control participants are healthy individuals used for comparison, in this case with 5 age, sex and ethnicity matched controls for each BP patient) were enrolled into the study. In total 113 (50.2%) BP patients and 49 (4.9%) control patients had PE. An independent association between eosinophil white blood cell count and diagnosis of BP was observed. BP patients with PE were generally significantly older than the other BP patients and had greater palmoplantar involvement (of the palms and soles of feet), whereas BP patients with normal eosinophil counts had greater involvement in mucosal surfaces (inside the nose, mouth, ears, genitals), the head and the neck. Patients with more severe BP were also noted to have significantly higher eosinophil counts than others with mild‐moderate BP. This study concludes that BP patients with severe peripheral eosinophilia were significantly older when their disease started, as well as proving the correlation between BP severity and PE.