This thesis explores the link between atopy and primary immunodeficiencies (PIDs), also known as inborn errors of immunity, in children. These genetic disorders often present with recurrent infections, inflammation, autoimmunity, and cancer. Atopic symptoms like eczema and asthma may mask the underlying immune dysfunction, leading to delayed diagnosis and complications. Through a review of the literature, the thesis discusses diagnostic challenges and outlines a differential approach to distinguish these conditions. It highlights the need for clearer criteria and further research to improve pediatric outcomes.