Currently, practitioners are increasingly having to consider the validity of the diagnosis being made. Similar clinical signs in different dermatoses require the differential diagnosis of diseases with a focus on pathognomonic signs. It helps correctly verify the diagnosis and provide proper medical care. Dermatologists see many patients with polymorphic rashes localized on open and closed areas of the skin. Moreover, skin lesions in different diseases may have the same localization. One such skin disease mimicking eczematous and photosensitive dermatoses is chronic actinic dermatitis (CAD), an immunologically mediated photodermatosis associated with delayed-type hypersensitivity reactions. It is a persistent photoinduced disease with itchy eczematous lesions on skin areas exposed to sunlight. We present a clinical case of a patient with CAD who was examined and treated at the Department of Dermatovenerology of the Samara State Medical University Clinic, demonstrating the clinical features of the disease course, its chronic recurrent nature, and some challenges in diagnosis due to similarity of clinical presentation with atopic dermatitis and ambiguous interpretation and opinion of specialists on etiology, pathogenesis and group identity of CAD.