The differing pathophysiologies that underlie COVID-19-associated perniosis and thrombotic retiform purpura: a case series.

BACKGROUND: There are two distinctive acral manifestations of COVID-19 embodying disparate clinical phenotypes. One is perniosis occurring in mildly symptomatic patients, typically children and young adults; the second is the thrombotic retiform purpura of critically ill adults with COVID-19. OBJECTIVES: To compare the clinical and pathological profiles of these two different cutaneous manifestations of COVID-19. METHODS: We compared the light microscopic, phenotypic, cytokine and SARS-CoV-2 protein and RNA profiles of COVID-19-associated perniosis with that of thrombotic retiform purpura in critical patients with COVID-19. RESULTS: Biopsies of COVID-19-associated perniosis exhibited vasocentric and eccrinotropic T-cell- and monocyte-derived CD11c+ , CD14+ and CD123+ dendritic cell infiltrates. Both COVID-associated and idiopathic perniosis showed striking expression of the type I interferon-inducible myxovirus resistance protein A (MXA), an established marker for type I interferon signalling in tissue. SARS-CoV-2 RNA, interleukin-6 and caspase 3 were minimally expressed and confined to mononuclear inflammatory cells. The biopsies from livedo/retiform purpura showed pauci-inflammatory vascular thrombosis without any MXA decoration. Blood vessels exhibited extensive complement deposition with endothelial cell localization of SARS-CoV-2 protein, interleukin-6 and caspase 3; SARS-CoV-2 RNA was not seen. CONCLUSIONS: COVID-19-associated perniosis represents a virally triggered exaggerated immune reaction with significant type I interferon signaling. This is important to SARS-CoV-2 eradication and has implications in regards to a more generalized highly inflammatory response. We hypothesize that in the thrombotic retiform purpura of critically ill patients with COVID-19, the vascular thrombosis in the skin and other organ systems is associated with a minimal interferon response. This allows excessive viral replication with release of viral proteins that localize to extrapulmonary endothelium and trigger extensive complement activation.

Skin Manifestations Associated with COVID-19: Current Knowledge and Future Perspectives.

BACKGROUND: Coronavirus disease-19 (COVID-19) is an ongoing global pandemic caused by the "severe acute respiratory syndrome coronavirus 2" (SARS-CoV-2), which was isolated for the first time in Wuhan (China) in December 2019. Common symptoms include fever, cough, fatigue, dyspnea and hypogeusia/hyposmia. Among extrapulmonary signs associated with COVID-19, dermatological manifestations have been increasingly reported in the last few months. SUMMARY: The polymorphic nature of COVID-19-associated cutaneous manifestations led our group to propose a classification, which distinguishes the following six main clinical patterns: (i) urticarial rash, (ii) confluent erythematous/maculopapular/morbilliform rash, (iii) papulovesicular exanthem, (iv) chilblain-like acral pattern, (v) livedo reticularis/racemosa-like pattern, (vi) purpuric "vasculitic" pattern. This review summarizes the current knowledge on COVID-19-associated cutaneous manifestations, focusing on clinical features and therapeutic management of each category and attempting to give an overview of the hypothesized pathophysiological mechanisms of these conditions.

Skin manifestations in patients hospitalized with confirmed COVID-19 disease: a cross-sectional study in a tertiary hospital.

BACKGROUND: COVID-19 cutaneous manifestations have been recently described and classified in five different clinical patterns, including acral erythema-edema (pseudo-chilblain), maculopapular exanthemas, vesicular eruptions, urticarial lesions, and livedo or necrosis. OBJECTIVES: The objective of this study was to examine the skin of hospitalized patients with a confirmed diagnosis of COVID-19 disease and describe the real prevalence of skin manifestations. METHODS: A cross-sectional study, which included hospitalized patients in Cruces University Hospital from April 14-30, 2020, with a laboratory-confirmed diagnosis of COVID-19 (with polymerase chain reaction and/or serology tests), was conducted. Entire body surface examination was performed by experienced dermatologists to search for cutaneous manifestations related to COVID-19 disease. RESULTS: From a sample of 75 patients, 14 (18.7%) developed cutaneous manifestations possibly related to COVID-19. We found six patients with acral erythema-edema (pseudo-chilblain) (42.8%), four patients with maculopapular exanthemas (28.6%), two patients with urticarial lesions (14.3%), one patient with livedo reticularis-like lesions (7.15%), and one patient with vesicular eruption (7.15%). CONCLUSIONS: Our study provides a more plausible relationship between the main cutaneous patterns and COVID-19 in hospitalized patients as all of them had a confirmatory laboratory test. Skin manifestations are frequent but mild with spontaneous resolution. These findings are nonspecific and can be similar to other viral infections and adverse drug reactions in hospitalized patients.