Background Chilblains ("COVID toes") are being seen with increasing frequency in children and young adults during the COVID‐19 pandemic. Detailed histopathological descriptions of COVID‐19 chilblains have not been reported, and causality of SARS‐CoV‐2 has not been established yet. Objective To describe histopathological features of Covid‐19 chilblains and explore the presence of SARS‐CoV‐2 in the tissue. Methods We examined skin biopsies from 7 paediatric patients presenting with chilblains during the COVID‐19 pandemic. Immunohistochemistry for SARS‐CoV‐2 was performed in all cases and electron microscopy in one. Results Histopathology showed variable degrees of lymphocytic vasculitis ranging from endothelial swelling and endothelialitis to fibrinoid necrosis and thrombosis. Purpura, superficial and deep perivascular lymphocytic inflammation with perieccrine accentuation, oedema, and mild vacuolar interface damage were also seen. SARS‐CoV‐2 immunohistochemistry was positive in endothelial cells and epithelial cells of eccrine glands. Coronavirus particles were found in the cytoplasm of endothelial cells on electron microscopy. Conclusions Although the clinical and histopathological features were similar to other forms of chilblains, the presence of viral particles in the endothelium and the histological evidence of vascular damage, support a causal relation of the lesions with SARS‐CoV‐2. Endothelial damage induced by the virus could be the key mechanism in the pathogenesis of COVID‐19 chilblains and perhaps also in a group of patients severely affected by COVID‐19 presenting with features of microangiopathic damage.

Inherited epidermolysis bullosa (EB) comprises a highly heterogeneous group of rare diseases characterized by fragility and blistering of skin and mucous membranes. Clinical features combined with immunofluorescence antigen mapping and/or electron microscopy examination of a skin biopsy allow to define the EB type and subtype. Molecular diagnosis is nowadays feasible in all EB subtypes and required for prenatal diagnosis. The extent of skin and mucosal lesions varies greatly depending on EB subtype and patient age. In the more severe EB subtypes lifelong generalized blistering, chronic ulcerations and scarring sequelae lead to multiorgan involvement, major morbidity and life-threatening complications. In the absence of a cure, patient management remains based on preventive measures, together with symptomatic treatment of cutaneous and extracutaneous manifestations and complications. The rarity and complexity of EB challenge its appropriate care. Thus, the aim of the present study has been to generate multicentre, multidisciplinary recommendations on global skin care addressed to physicians, nurses and other health professionals dealing with EB, both in centres of expertise and primary care setting.

Epidermal differentiation disorders (EDDs) encompass inherited conditions characterized by abnormal epidermal differentiation, including nonsyndromic and syndromic subtypes with more extensive cutaneous involvement or palmoplantar keratoderma. Nonsyndromic EDDs (nEDDs) are defined as disorders that primarily affect large areas of skin and adnexal structures without alterations in extracutaneous tissues resulting from the underlying genetic change. To facilitate the development of targeted therapies and to provide clinicians with clearer therapeutic guidance, we have developed a new nomenclature for EDDs that includes the causative altered gene and the nEDD subgroup designation, sometimes with a clinical or histological descriptor or acronym. Historically, many nEDDs have been named on the basis of phenotypic characteristics or associations that are now considered outdated or inappropriate. For example, the term ‘harlequin ichthyosis’ evokes potentially stigmatizing images. Similarly, the word ‘ichthyosis’ is derived from the Greek ichthys, meaning fish, and the Greek hystrix, meaning porcupine, further emphasizing the need to abandon derogatory terminology. As a result, the clinical relevance of the previous classification, which included eponymous and/or descriptive titles, has diminished. In the new, gene-based classification, old terms considered pejorative, such as ichthyosis, vulgaris, hystrix and harlequin have been eliminated and eponyms have been replaced. Among the 53 genetically distinct nEDDs are conditions formerly known as autosomal recessive congenital ichthyosis, erythrokeratodermia variabilis et progressiva, Hailey–Hailey disease and Darier–White disease. This review outlines the updated nomenclature and classifications of nEDDs, linked to detailed clinical descriptions and representative photographs to guide practitioners.