A practical guide to recognize allergic and immunologic skin diseases: diagnosis at first sight

Allergic and immunologic skin diseases are becoming increasingly common and this requires clinicians to be able to recognize and diagnose them. A joint meeting (GET TOGETHER 2022) of the Italian Society of Allergy, Asthma and Clinical Immunology (SIAAIC) and the Italian Society of Allergological, Occupational and Environmental Dermatology (SIDAPA) aimed to review the current knowledge on the differential diagnosis of contact dermatitis, atopic dermatitis, hereditary angioedema, urticaria, and cutaneous mastocytosis. The most important aspects to take into consideration when faced with a new cutaneous manifestation are the clinical features of the lesions, their distribution, age of onset, and comorbidities/aggravating factors. The document does not aim to provide an exhaustive and comprehensive description of all allergic and immunologic skin diseases. Instead, it should be a reference tool for the clinician who is faced with the onset of a new skin manifestation and its differential diagnosis.