Atopic dermatitis (AD) prevalence is rising worldwide. Literature data suggest the incidence of AD in developing countries is gradually getting close to that of developed ones, in which AD affects 20% of the paediatric population. Such an increment, associated with significant variations in prevalence among the various countries, underlines the importance of environmental factors in the disease onset. Among these, great importance is given to hygiene, intestinal microbiota, exposure to bacterial endotoxins, outdoor living with contact to animals, atmospheric pollution, weather, and diet. Genetic (alteration of the skin barrier function) as well as immunologic factors concur with the environmental ones. Only the systematical study of all these elements can best elucidate AD epidemiology.

Irritant or allergic contact dermatitis usually presents as an eczematous process, clinically characterized by erythematoedematovesicous lesions with intense itching in the acute phase. Such manifestations become erythematous-scaly as the condition progresses to the subacute phase and papular-hyperkeratotic in the chronic phase. Not infrequently, however, contact dermatitis presents with noneczematous features. The reasons underlying this clinical polymorphism lie in the different noxae and contact modalities, as well as in the individual susceptibility and the various targeted cutaneous structures. The most represented forms of non-eczematous contact dermatitis include the erythema multiforme-like, the purpuric, the lichenoid, and the pigmented kinds. These clinical entities must obviously be discerned from the corresponding “pure” dermatitis, which are not associated with contact with exogenous agents.

Current epidemiological data support the association between psoriasis and cardiovascular (CV) risk, in apparent correlation with psoriasis severity. Although less unanimously, evidence of an increased prevalence of CV diseases among psoriasis patients has been reported, including ischemic heart disease, cerebrovascular, peripheral vascular and heart structural disorders. In particular, various studies showed a correlation between psoriasis and major CV events (i.e., myocardial infarction, stroke), while others investigated subclinical changes of blood vessels, such as intima-media thickness increase, arterial stiffness and coronary artery calcification. A series of different mechanisms, like traditional CV risk or iatrogenic risk factors, inflammation, hemostasis dysregulation, hyperhomocysteinemia, and shared genetic susceptibility, are thought to underlie this epidemiological association. Among these elements, inflammation and its related cytokine milieu, including Th1-mediated response and Th17/Treg imbalance, C reactive protein and the newly implicated osteopontin are considered to play a primary role, even if yet to be fully understood.

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Over the last years, data have been accumulating regarding a possible association between alcohol and psoriasis. While it is still unclear whether alcohol misuse represents a true risk factor or merely an epiphenomenon of the cutaneous disease, a number of studies support the role of ethanol and its metabolites as triggering factors of psoriasis. A drinking habit also appears to exacerbate a preexisting psoriasis, and the magnitude of alcohol consumption may be related to both a higher incidence and severity of psoriasis. Evidence also shows that deaths from alcohol-related causes are significantly more frequent in patients with psoriasis than in normal controls. Alcohol consumption may adversely affect psoriasis through multiple mechanisms, such as increased susceptibility to infections, stimulation of lymphocyte and keratinocyte proliferation, and production of proinflammatory cytokines. Moreover, alcohol misuse can predispose to a greater risk of liver disease and potential drug interactions. Alcoholic and non-alcoholic liver diseases have both been found to be common in psoriatic patients. Tumor necrosis factor (TNF)-alpha, a key cytokine in psoriasis pathogenesis, has been found to have a crucial role in alcoholic hepatitis, and small preliminary studies have evaluated the effect of anti-TNF therapy in this condition. However, the use of anti-TNF-α drugs in alcoholic hepatitis is still controversial and needs to be further investigated. In this review, the relationship between alcohol and psoriasis will be reviewed and discussed, taking also into account recent findings related to liver disease and therapeutic implications.