Atopic dermatitis reconsidered: Clinical mimics and diagnostic pearls.

Atopic dermatitis (AD) is a chronic, pruritic inflammatory skin condition with a complex pathogenesis and variable clinical presentation, often overlapping with other dermatologic diseases. This article considers the differential diagnoses for AD, emphasizing the importance of accurately distinguishing it from both common and rare conditions. Among inflammatory dermatoses, seborrheic dermatitis, psoriasis, allergic and irritant contact dermatitis, lichen simplex chronicus, and pityriasis rosea share overlapping features but can be differentiated based on history, distribution, and morphology. Infectious mimickers include scabies, tinea corporis, impetigo, and secondary syphilis, each with unique clinical or diagnostic markers. High priority diagnoses such as neoplastic diseases (mycosis fungoides), autoimmune conditions (dermatomyositis), nutritional deficiencies (zinc, niacin), genetic syndromes (Netherton, severe dermatitis-allergies-metabolic wasting), primary immunodeficiencies (hyper-IgE, DiGeorge, Wiskott-Aldrich syndrome), and drug eruptions require special consideration. Despite growing interest in immunologic and molecular biomarkers for AD, no single biomarker offers diagnostic certainty. Advances in diagnostic tools such as epidermal profiling and RNA sequencing may pave the way for more personalized approaches to dermatologic care. Currently, accurate diagnosis of AD remains clinical and requires vigilance, especially when disease course and response to therapy deviate from expected patterns.