Background: Atopic dermatitis (AD) is a chronic, relapsing inflammatory dermatosis that is characterized by pruritus, xerosis, and age-dependent clinical heterogeneity. Accurately diagnosing AD remains challenging due to the absence of specific biomarkers and the broad spectrum of conditions that may mimic its presentation. A wide range of inflammatory, infectious, and genetic disorders resemble AD, including seborrheic dermatitis, psoriasis, contact dermatitis, scabies, dermatophytosis, and nummular eczema, as well as rare immunodeficiency and metabolic conditions. This review summarizes the evolution of the clinical features of pediatric AD across infancy, childhood, and adolescence, with a focus on key differential diagnoses. Recognizing age-specific patterns and potential mimickers is essential for improving diagnostic accuracy and guiding appropriate management in pediatric AD. Methods: This study was designed as a narrative review. A structured literature search was conducted of PubMed/MEDLINE for studies published between January 2001 and March 2026 using predefined keywords related to AD, childhood, diagnosis, and differential. Clinical trials, randomized controlled trials, systematic reviews, meta-analyses, and guidelines or consensus documents were included. Studies focusing exclusively on adults or lacking clinical relevance were excluded. A qualitative synthesis was performed due to the heterogeneity in study designs and outcomes. Results: This review demonstrates that pediatric atopic dermatitis exhibits marked age-dependent clinical heterogeneity, with distinct morphological features and lesion distribution patterns across infancy, childhood, and adolescence. Furthermore, the substantial clinical overlap with a broad spectrum of inflammatory, infectious, and genetic disorders-combined with the absence of specific diagnostic biomarkers-significantly complicates accurate differential diagnosis and increases the risk of misclassification. Conclusions: The recognition of age-specific patterns and potential mimickers is essential for improving diagnostic accuracy and guiding appropriate management in pediatric AD.

Background Tinea corporis is a common superficial fungal infection caused by dermatophytes. It typically presents as well-defined, pruritic, annular papules and plaques with central hypopigmentation. The differential diagnosis includes pityriasis rosea, nummular dermatitis, plaque psoriasis, tinea versicolor, granuloma annulare, and discoid lupus. This article compares different presentations of tinea corporis in various skin types as classified by the Fitzpatrick scale. Recognizing varying presentations of tinea in patients of different skin tones will aid in early and appropriate diagnosis and treatment.

Paraphenylenediamine (PPD) is an aromatic amine that was first manufactured in Germany by Hofmann in 1833. It is primarily employed for its antioxidant and staining properties and is found in rubber goods, printer ink, photographic supplies, textiles and footwear, henna tattoos, and hair dyes. As it is a prehapten that can cross the skin barrier easily, it can be detected in plasma, urine, and faeces after application of hair dye within half an hour. The molecular properties of PPD allow hair dye to effectively permeate the skin, resulting in sensitisation and the eventual development of allergic contact dermatitis. Redness, pain, pruritus, dryness, prickling sensation, burning or tingling sensation, and discomfort are some of the symptoms of hair dye dermatitis. Clinically, allergic reactions to PPD may vary from localised lesions, such as eyelid eczema, nummular eczema, or hand eczema, to disseminated forms, such as airborne contact dermatitis, prurigo-nodularis-like, or erythroderma-like. Systemic contact dermatitis (SCD) is a severe, delayed immune-mediated reaction (type IV hypersensitivity reaction) to PPD, a common ingredient in hair dyes and temporary "black henna" tattoos, causing widespread eczema, intense itching, redness, swelling, and sometimes even asthma-like symptoms or lymph node swelling, occurring far beyond the direct contact area after initial sensitization, and requires strict avoidance of PPD in all forms. This is a case of a woman who presented with symmetrical drug-related intertriginous and flexural exanthema (SDRIFE)-like features, a type of SCD post hairdye application, but without any history of drug intake that is relevant for Baboon syndrome (synonymous with SDRIFE).

Eczema is an inflammatory skin condition that affects individuals of all ages worldwide. Patients may develop various forms of eczema, including atopic dermatitis, contact dermatitis, which is often associated with an allergic response to various stimuli, dyshidrotic eczema which develops on the palms and soles, asteatotic dermatitis that predominantly occurs in elderly patients, nummular eczema characterized by its cylindrical shape lesions and seborrheic dermatitis often located on patient's scalps, back, face and chest. Extensive studies have been conducted on atopic dermatitis, however, limited information such as their etiology, effect on the immune system and potential treatments are available on the other types of eczema. The socioeconomic impacts of eczema include the cost of conventional treatments such as corticosteroids, immunosuppressive agents and phototherapy, expenses related to specialists' consultation and the effect on work and school productivity. The impact of atopic dermatitis on patients' quality of life, social functioning and individual healthcare expenses has been extensively studied in other countries but remains underreported in South Africa. Reports have estimated the annual direct and indirect costs in Australia, the United Kingdom and the United States, however reports are limited for South Africa. This study aimed to provide information on the different types of eczema's etiology, their respective socioeconomic impact in South Africa in correlation to the above mentioned inflated yearly cost, and conventional, targeted and alternative treatments commercially available. Several knowledge gaps were identified in this study, including the limited availability of information on asteatotic dermatitis, dyshidrotic dermatitis and nummular eczema, the effect most commercially available treatments have on other eczema subtypes and an in-depth review of the socioeconomic impact of eczema within the African continent.

Atopic dermatitis and contact dermatitis are among the most common dermatologic conditions encountered by the primary care clinician. Their presentation varies and can mimic infectious and other noninfectious conditions, making a thorough history essential, with particular emphasis on exposure to environmental and occupational irritants, as well as recognition of commonly affected sites. For all of these conditions, control of symptoms is often the goal of treatment, starting with general supportive care measures like frequent emollient use and often relying on topical steroidal and nonsteroidal agents as first-line therapies.

Although dermatological manifestations are common in hepatitis C virus (HCV) infection, nummular eczema is rarely reported in this context. We describe the case of a 73-year-old man with a seven-month history of pruritic lesions on the posterior thorax, unresponsive to symptomatic treatment. Physical and dermoscopic examination revealed well-demarcated, coin-shaped plaques with peripheral erythema and fine desquamation. Histopathology confirmed chronic inflammatory dermatitis. Laboratory tests showed elevated transaminases and high HCV viral load. The patient had a history of blood transfusion two decades prior but no prior HCV diagnosis. He was treated with a 12-week course of glecaprevir/pibrentasvir, which resulted in complete resolution of skin lesions and normalization of liver enzymes within one month. No adverse events were recorded. This case highlights the importance of recognizing atypical dermatological signs as possible early indicators of HCV infection and supports the effectiveness of direct-acting antivirals in resolving both hepatic and extrahepatic manifestations.

Nummular eczema (NE) is a distinctive eczematous dermatitis characterized by an eruption of coin-shaped erythematous, edematous, vesicular, and crusted patches that tend to expand as papulovesicular satellite lesions appear at the periphery and fuse with the main plaque. This pruritic disorder classically affects the extensor aspect of the extremities, trunk, and buttocks. Patients generally report poor quality of life, demanding early and effective treatment. Although topical therapy is the mainstay of management, treatment escalation may be required in severe cases. Dupilumab, a human monoclonal antibody that targets both IL-4 and IL-13, has shown efficacy for moderate to severe atopic dermatitis and other immune-mediated disorders. Here, we report a six-year-old boy with severe and extremely pruritic NE unresponsive to topical and classic systemic treatments, showing complete and maintained remission of all skin signs and symptoms under dupilumab treatment.

Warts, Hypogammaglobulinemia, Infections, and Myelokathexis (WHIM) syndrome is a rare immunodeficiency caused by gain-of-function mutations in the chemokine receptor CXCR4. While human papillomavirus (HPV) skin infection (warts) is the dermatological hallmark of the disease, individuals with WHIM have high rates of other skin manifestations that may aid early diagnosis and management. This study was a retrospective review of medical records from a United States National Institutes of Health natural history cohort of patients with WHIM syndrome seen between 2005 and 2024, including a cross-sectional analysis of cutaneous manifestations and CXCR4 variants. The cohort compromised 45 patients with genetically confirmed WHIM syndrome, 16 men and 29 women, with a mean age of 33.3 years (range, 0-69 years) and mean age at diagnosis of 20.4 years (range, 0-59 years). The cohort exhibited a range of skin manifestations which included cutaneous infections with HPV in 34 (76%) patients, bacteria in 32 (71%) patients, other viruses in 27 (60%) patients, and fungi in 25 (56%) patients. Inflammatory conditions included six (13%) patients with seborrheic dermatitis, five (11%) with contact dermatitis, four (9%) with psoriasis, three (7%) with nummular eczema, and 13 (29%) with other eczematous dermatitis. Despite the young median age, seven (16%) patients had skin cancer. All seven patients had CXCR4 truncation mutations, while those with a missense mutation (E343K) generally had fewer skin manifestations. Our study found that WHIM syndrome is associated with diverse infectious, inflammatory, and neoplastic skin conditions beyond HPV skin infection.

Facial discoid dermatosis (FDD) is a condition characterized by papules-plaques primarily affecting the face. FDD has been associated with psoriasis, seborrheic dermatitis, and pityriasis rubra pilaris. We conducted a retrospective multicenter study with 13 patients diagnosed with FDD in Spain (2014-2022). Patient demographics, clinical presentations, histopathological findings, and treatment outcomes were collected. FDD shows as erythematous-orange, nummular papules and/or plaques with dry scales that primarily affect the facial region. Histopathological analysis revealed a consistent pattern of psoriasiform hyperplasia with confluent parakeratosis, without neutrophils within the epidermal layers. This study provides essential insights into the clinical and histopathological features of FDD within a predominantly Caucasian patient cohort. The presence of distinct clinical features and consistent histological findings underscores the uniqueness of FDD. However, the variability in histological features and persistence of lesions despite various treatments highlight the need for further research to better understand the pathogenesis of FDD and develop effective therapies.