Coronavirus disease pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) primarily affects the epithelium of the airways.With the increasing involvement of dermatologist in management of this crisis, cutaneous symptoms gained more and more attention. In this review, we will describe cutaneous symptoms of patients of all ages in association with COVID-19.We will focus on such disorders that are caused by direct action of SARS-CoV-2 on tissues, complement, and coagulation system and on nonspecific eruption of the systemic viral infection. Drug-induced reactions are only mentioned in the differential diagnoses. Although more systematic investigations are warranted, it becomes clear that some symptoms are clinical signs of a milder COVID-19 course, while others are a red flag for a more severe course. Knowledge of the cutaneous manifestations of COVID-19 may help in early diagnosis, triage of patients, and risk stratification.

Acne is a very common and disfiguring disease that affects mostly adolescents and, to some extent, adults. The objective of our study was to estimate the adverse effects after isotretinoin by treatment of 3,525 patients due to acne vulgaris in a 5-year observation. Retrospective, comparative study was carried out in Poland and Romania from January 2012 to August 2016. Inclusion criteria into this study were moderate, severe, and nodulocystic inflammatory acne vulgaris. Exclusion criteria were mild acne, pregnant, and lactating women. Statistical analysis was carried out using T test and Chi square. All patients were treated with oral isotretinoin. Patient age ranged from 13-35 years. Dry lips was the most commonly reported adverse effect, affecting 100% of users, followed by xerosis (94.97%) and facial erythema (66.21%). Of all adverse effects, psychiatric symptoms accounted for 25.16%; eye lesions accounted for 8.96%. In lab investigations an increase in the level of total cholesterol and serum triglycerides was observed. This study documents the adverse effect profile of isotretinoin in a large number of patients collected over a period of 4 years. Side effects were mild and well tolerated and did not necessitate stopping the treatment. However, it is important to educate patients about this potential consequence.

Summary The current COVID‐19 pandemic is caused by the SARS‐CoV‐2 coronavirus. The initial recognized symptoms were respiratory, sometimes culminating in severe respiratory distress requiring ventilation, and causing death in a percentage of those infected. As time has passed, other symptoms have been recognized. The initial reports of cutaneous manifestations were from Italian dermatologists, probably because Italy was the first European country to be heavily affected by the pandemic. The overall clinical presentation, course and outcome of SARS‐CoV‐2 infection in children differ from those in adults as do the cutaneous manifestations of childhood. In this review, we summarize the current knowledge on the cutaneous manifestations of COVID‐19 in children after thorough and critical review of articles published in the literature and from the personal experience of a large panel of paediatric dermatologists in Europe. In Part 1, we discuss one of the first and most widespread cutaneous manifestation of COVID‐19, chilblain‐like lesions. In Part 2, we review other manifestations, including erythema multiforme, urticaria and Kawasaki disease‐like inflammatory multisystemic syndrome, while in Part 3, we discuss the histological findings of COVID‐19 manifestations, and the testing and management of infected children, for both COVID‐19 and any other pre‐existing conditions.

Summary The current COVID‐19 pandemic is caused by the SARS‐CoV‐2 coronavirus. The initial recognized symptoms were respiratory, sometimes culminating in severe respiratory distress requiring ventilation, and causing death in a percentage of those infected. As time has passed, other symptoms have been recognized. The initial reports of cutaneous manifestations were from Italian dermatologists, probably because Italy was the first European country to be heavily affected by the pandemic. The overall clinical presentation, course and outcome of SARS‐CoV‐2 infection in children differ from those in adults, as do the cutaneous manifestations of childhood. In this review, we summarize the current knowledge on the cutaneous manifestations of COVID‐19 in children after thorough and critical review of articles published in the literature and from the personal experience of a large panel of paediatric dermatologists in Europe. In Part 1, we discussed one of the first and most widespread cutaneous manifestations of COVID‐19, chilblain‐like lesions. In this part of the review, we describe other manifestations, including erythema multiforme, urticaria and Kawasaki disease‐like inflammatory multisystemic syndrome. In Part 3, we discuss the histological findings of COVID‐19 manifestations, and the testing and management of infected children for both COVID‐19 and any other pre‐existing conditions.

Summary The current COVID‐19 pandemic is caused by the SARS‐CoV‐2 coronavirus. The initial recognized symptoms were respiratory, sometimes culminating in severe respiratory distress requiring ventilation, and causing death in a percentage of those infected. As time has passed, other symptoms have been recognized. The initial reports of cutaneous manifestations were from Italian dermatologists, probably because Italy was the first European country to be heavily affected by the pandemic. The overall clinical presentation, course and outcome of SARS‐CoV‐2 infection in children differ from those in adults as do the cutaneous manifestations of childhood. In this review, we summarize the current knowledge on the cutaneous manifestations of COVID‐19 in children after thorough and critical review of articles published in the literature and from the personal experience of a large panel of paediatric dermatologists in Europe. In Part 1, we discuss one of the first and most widespread cutaneous manifestations of COVID‐19, chilblain‐like lesions, and in Part 2 we expanded to other manifestations, including erythema multiforme, urticaria and Kawasaki disease‐like inflammatory multisystemic syndrome. In this part of the review, we discuss the histological findings of COVID‐19 manifestations, and the testing and management of infected children for both COVID‐19 and any other pre‐existing conditions.

Green nails, also known as chloronychia or green nail syndrome, are characterized by green discoloration of the nail plate (greenish-yellow, greenish-brown, greenish-black), proximal chronic non-tender paronychia, and distolateral onycholysis. The cause is Pseudomonas aeruginosa infection of the nail plate in persons whose hands are constantly exposed to water, soaps, and detergents or are subject to mechanical trauma, especially in the elderly. Green or black coloration of the nails should raise suspicion for Pseudomonas infection and be treated with an oral quinolone (ciprofloxacin), particularly in aged patients. We present three cases of green nails in elderly persons.

Aplasia cutis congenita is a rare malformation characterized by localized congenital absence of the skin. It rarely occurs on the trunk and limbs, and can occur in isolation or as part of a heterogeneous group of syndromes. We report a case of a 4-day-old boy with a 5.6-cm- diameter tumor, with a central crust, non-indurate and no inflammatory rim; localized on the scalp and a small, atrophic hairless scar appeared 6 months later (approximately 5cm in length) at the site of the previous tumor.

IL-9 is present in psoriatic lesions and is produced by lymphocytes. However, it is not known whether this cytokine is induced by relevant pathogenic triggers of psoriasis, such as Streptococcus pyogenes. Here we addressed the production of IL-9 in response to various pathogens in a psoriatic ex vivo model. Extracts of S. pyogenes and Candida albicans triggered the production of IL-9 and also IL-17A and IFN-γ. This induction was dependent on the interaction between CLA T cells and epidermal cells. Neutralization of IL-9 reduced S. pyogenes-induced IL-17A production by CLA T cells but had no effect on IFN-γ production. Also, IL-9 increased the survival of circulating psoriatic CLA T cells. Co-cultures from patients with guttate or plaque psoriasis with S. pyogenes produced similar amounts of IL-9. High cytokine responses in streptococcal-driven guttate patients paralleled peaks in Psoriasis Area Severity Index and anti-streptolysin O levels. Our results confirm that IL-9 promotes inflammation in psoriasis by up-regulating IL-17A production and support the clinical association of the immune response by streptococcal-sensitized CLA T cells with this cytokine, especially in guttate psoriasis.