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Background: The abundance of publications of COVID‐19‐induced chilblains has resulted in a confusing situation. Methods: This is a prospective single‐institution study from 15 March to 13 May 2020. Thirty‐two patients received PCR nasopharyngeal swabs. Of these, 28 patients had a thoracic CT‐scan, 31 patients had blood and urine examinations, 24 patients had skin biopsies including immunohistochemical and direct immunofluorescence studies, and four patients had electron microscopy. Results: COVID‐19‐induced chilblains are clinically and histopathologically identical to chilblains from other causes. Although intravascular thrombi are sometimes observed, no patient had a systemic coagulopathy or severe clinical course. The exhaustive clinical, radiological, and laboratory work‐up in this study ruled‐out other primary and secondary causes. Electron microscopy revealed rare, probable viral particles whose core and spikes measured from 120 to 133 nm within endothelium and eccrine glands in two cases. Conclusion: This study provides further clinicopathologic evidence of COVID‐19‐related chilblains. Negative PCR and antibody tests do not rule‐out infection. Chilblains represent a good prognosis, occurring later in the disease course. No systemic coagulopathy was identified in any patient. Patients presenting with acral lesions should be isolated, and chilblains should be distinguished from thrombotic lesions (livedo racemosa, retiform purpura, or ischemic acral necrosis). [ABSTRACT FROM AUTHOR]

Objective: To evaluate the clinical, histopathological, and immunopathological findings of the pathergy test in Thai patients with Behcet's disease. Methods: A pathergy test using the needle prick method with a 20G disposable needle after cleaning with 70% alcohol was performed in 5 patients (4 females and 1 male), with Behcet's disease according to International Study Group (ISG) criteria. The skin was pricked making a 45o angle with the skin surface to a depth of 3 mm at an avascular and hairless point of both forearms symmetrically. After 4 and 48 hours, the test sites were evaluated clinically and skin biopsies were performed at a prick site on the right forearm after 4 hours for direct immunofluorescence study and after 48 hours at the prick site on the left forearm for histopathological study. Results: Clinical pathergy tests were positive (a single papular lesion at the needle prick site) in 3 out of 5 patients at 48 hours. No response was observed at 4 hours. Direct immunoflurorescence study showed no deposition of immnoglobulins (IgG, IgM, IgA) and C3 in any case. The histopathological findings 48 hours after the test revealed definite neutrophilic infiltration around a superficial vascular plexus in 4 cases, in addition, one of these had endothelial cell swelling with red blood cell extravasation. The rest (1 case) showed nonspecific findings. Conclusion: We conclude that a pathergy test is a useful tool for the diagnosis of Behcet's disease. The intradermal needle prick method using 20G disposable needle after cleaning the skin with 70% alcohol, yields results of moderately high sensitivity. The results should be evaluated at 48 hours both clinically and histopathologically.

Background Bullous pemphigoid (BP) is an acquired autoimmune blistering disease characterized by subepidermal blister formation, in vivo linear deposition of immunoglobulin G (IgG) and complements at the dermal–epidermal junction (DEJ). The circulating IgG autoantibodies are directed against two epidermal hemidesmosomal glycoproteins: BP180, also known as type XVII collagen (COL17), and BP230. In addition, recent studies have shown that IgE autoantibodies may be involved in the pathogenesis of BP, although in vivo IgE deposition in lesional skin has not been fully characterized in large numbers of BP patients. Objective This study investigated the incidence of in vivo deposition of IgE autoantibodies at the DEJ in lesional skin from a large number of BP patients. Methods Peri-lesional skin samples from 100 patients who met the clinical and histopathological criteria for BP were investigated by direct immunofluorescence for the deposition of autoantibodies and complement. Patients’ sera were also investigated by enzyme-linked immunosorbent assay and indirect immunofluorescence. Results 18% of BP patients were found to show IgE deposition at the DEJ. Disease severity, clinical course and outcome did not differ between IgE-positive and IgE-negative patients. In 3 IgE-positive cases, IgG was undetectable in vivo , and these cases showed atypical manifestations. Conclusion The results of in vivo IgE deposition may not be useful in predicting the disease course of BP, although predominant IgE deposition could alter the pattern of clinical manifestations. [ABSTRACT FROM AUTHOR]