Summary Atopic dermatitis (AD) is a common disease affecting both children and adults. AD develops from a complex interplay between environmental, genetic, immunologic and biochemical factors. Genetic factors predispose atopic subjects to mount exaggerated Th2 responses and to a poorly efficient epidermal barrier, which may be sufficient to initiate inflammation in the skin and may favor allergic sensitization. Thus AD can present with different clinical pheno‐types. AD is classically distinguished into an intrinsic and extrinsic form, which are clinically identical but the former lacks high level specific IgE and is not associated with respiratory atopy. Although in many cases AD presents with monotonous eczematous lesions on the face, neck and skin folds, it may also present with other features. Very common is nummular eczema, which in many instances may be the dominant expression of AD. In other patients, AD affects limited areas (periorificial eczema, nipple eczema, cheilitis, hand eczema) or its main presentation is with excoriated papules and nodules (atopic prurigo). In conclusion, AD is a multifaceted disease affecting patients with epidermal barrier dysfunction and dry and sensitive skin. The recognition of the less common AD phenotypes is essential for proper patient management.

Psoriasis is a common chronic inflammatory, immune-mediated skin disease that is frequently associated with comorbidities including psoriatic arthropathy, chronic inflammatory bowel diseases, and cardio-metabolic disorders. In particular, nonalcoholic fatty liver disease affects about half of patients, Crohn's disease 0.5% and celiac disease 0.2-4.3% of patients with psoriasis. Some shared genetic traits as well as common inflammatory pathways may underlie these associations. The presence of comorbidities has important implications in the global approach to patients. In particular, traditional systemic antipsoriatic agents could negatively affect cardio-metabolic comorbidities as well as nonalcoholic fatty liver disease and may have important interactions with drugs commonly used by psoriasis patients. Moreover, patients with psoriasis should be encouraged to drastically correct their modifiable cardiovascular and liver risk factors, in particular obesity, alcohol consumption, and smoking habit, because this could positively affect both psoriasis and their life expectance.

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Adult onset Still's disease (AOSD) is a systemic inflammatory disorder of unknown etiology and pathogenesis characterized by high spiking fever, arthralgia or arthritis, sore throat, lymphadenopathy, hepatosplenomegaly, serositis, and transient cutaneous manifestations. Although more common in children, cases are seen also in adults. Cutaneous involvement is common and may be suggestive for the diagnosis. A case of AOSD in a 35-year-old man is reported here, presenting with urticarial maculopapular rash of trunk, high spiking fever, acute respiratory distress syndrome, and myopericarditis. Skin biopsy showed interstitial and perivascular mature CD15(+) neutrophils. A comprehensive review of literature showed that cutaneous involvement occurs in about 80 % of patients, with various clinical presentations. The most common skin manifestation is an evanescent salmon pink or erythematous maculopapular exanthema, predominantly on the trunk and proximal limbs, with rare involvement of face and distal limbs. Less common manifestations include persistent erythematous plaques and pustular lesions. A constant histopathologic finding is the presence of interstitial dermal neutrophils aligned between the collagen bundles. This pattern may provide an easy accessible clue for the definitive diagnosis of AOSD and exclude other diagnosis such as drug eruptions or infectious diseases.

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