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.

Background: Janus kinase (JAK) inhibition is a new mode of action in atopic dermatitis (AD); clarity about drug class safety considerations in the context of AD is important. Baricitinib, an oral, reversible, selective inhibitor of JAK1/JAK2, is in late‐stage development for adult patients with moderate‐to‐severe AD.Objective: To report pooled safety data for baricitinib in patients with moderate‐to‐severe AD in the clinical development program including long‐term extension (LTE) studies.Methods: This analysis included patient‐level safety data from six double‐blinded, randomized, placebo‐controlled studies (one phase 2 and five phase 3), one double‐blinded, randomized, LTE study and one open‐label LTE study, reported in three data sets: placebo‐controlled, 2‐mg – 4‐mg extended and All‐bari AD. Safety outcomes include treatment‐emergent adverse events, adverse events of special interest and abnormal laboratory changes. Proportions of patients with events and incidence rates were calculated.Results: Data were collected for 2531 patients who were given baricitinib for 2247 patient‐years (median duration 310 days). The frequency of serious infections, opportunistic infections and conjunctival disorders was low and similar between treatment groups in the placebo‐controlled period. The most common serious infections were eczema herpeticum [n = 11, incidence rates (IR) = 0.5], cellulitis (n = 6, IR = 0.3) and pneumonia (n = 3, IR = 0.1). There were four opportunistic infections (IR = 0.2). No malignancies, gastrointestinal perforations, positively adjudicated cardiovascular events or tuberculosis were reported in the placebo‐controlled period in baricitinib‐treated patients. Frequency of herpes simplex was higher in the 4‐mg group (6.1%) vs. the 2‐mg (3.6%) and placebo group (2.7%); IRs in the extended data set (2‐mg IR = 9.6; 4‐mg IR = 14.5) were lower vs. the placebo‐controlled data set (2‐mg IR = 12.4; 4‐mg IR = 21.3). In the All‐bari AD data set, there were two positively adjudicated major adverse cardiovascular events (2‐mg group): two venous thrombosis events (4‐mg group) and one death.Conclusion: This integrated safety analysis in patients with moderate‐to‐severe AD confirms the established safety profile of baricitinib.

CANDLE syndrome (Chronic Atypical Neutrophilic Dermatosis with Lipodystrophy and Elevated temperature) is a rare, genetic autoinflammatory disease due to abnormal functioning of the multicatalytic system proteasome – immunoproteasome. Several recessive mutations in different protein subunits of this system, located in one single subunit (monogenic, homozygous or compound heterozygous) or in two different ones (digenic, compound heterozygous) cause variable defects in catalytic activity of the proteasome – immunoproteasome. The final result is a sustained production of type 1 interferons (IFNs) that can be very much increased by banal triggers such as cold, stress or viral infections. Patients start very early in infancy with recurrent or even daily fevers, characteristic skin lesions, wasting and a typical fat loss, all conferring the patients a unique and unmistakable phenotype. So far, no treatment has been effective for the treatment of CANDLE syndrome; the JAK inhibitor baricitinib seems to be partially helpful. In this article, a review in depth all the pathophysiological, clinical and laboratory features of CANDLE syndrome is provided.