Hypereosinophilic syndrome (HES) encompasses a heterogeneous and complex group of different subtypes within the wider group of hypereosinophilic disorders. Despite increasing research interest, several unmet needs in terms of disease identification, pathobiology, phenotyping, and personalized treatment remain to be addressed. Also, the prospective burden of non-malignant HES and, more in general, HE disorders is currently unknown. On a practical note, shortening the diagnostic delay and the time to an appropriate treatment approach probably represents the most urgent issue, even in light of the great impact of HES on the quality of life of affected patients. The present document represents the first action that the Italian Society of Allergy, Asthma, and Clinical Immunology (SIAAIC) has finalized within a wider project aiming to establish a collaborative national network on HES (InHES—Italian Network on HES) for patients and physicians. The first step of the project could not but focus on defining a common language as well as sharing with all of the medical community an update on the most recent advances in the field. In fact, the existing literature has been carefully reviewed in order to critically integrate the different views on the topic and derive practical recommendations on disease identification and treatment approaches.

Autoimmune skin disorders, including Psoriasis, Lichen Planus, Vitiligo, Atopic Dermatitis, and Alopecia Areata, arise from a combination of genetic predisposition, external factors, and immunological dysfunction. It is well-documented that there is a strong correlation between autoimmune thyroid diseases and a range of dermatological disorders, especially urticaria. This review investigates possible links between autoimmune thyroiditis and a broader spectrum of autoimmune skin conditions, analyzing shared genetic markers, immunological mechanisms, and clinical correlations. Common pathogenic mechanisms include disrupted immune tolerance and oxidative stress, leading to chronic inflammation. Genetic factors, such as IL-23 receptor gene variants, increase the risk for Psoriasis, Alopecia Areata, and Hashimoto’s thyroiditis. Additionally, CTLA-4 mutations enhance susceptibility to autoimmune thyroid and skin disorders. Shared genetic susceptibility was also reported in Lichen Planus and Vitilgo, even if different genetic loci might be involved. The breakdown of the immune system can determine a pro-inflammatory state, facilitating the development of autoimmunity and auto-antibody cross-reactions. The presence of similar antigens in skin cells and thyrocytes might explain why both tissues are affected. The significant overlap between these conditions emphasizes the necessity for a comprehensive diagnosis workup and treatment. Future research should focus on clarifying specific immunological pathways and identifying novel biomarkers.

Allergen-specific immunotherapy (AIT) is a proven efficacy treatment for allergic rhinitis (AR), asthma, and Hymenoptera venom allergy, but its use in food allergy (FA) is still under investigation.