Diagnostic value of cutaneous manifestation of SARS-CoV-2 infection

Abstract

Background: One of the challenging aspects of SARS-CoV-2 infection is its diverse multisystemic disease presentation.

Objectives: To evaluate the diagnostic value of cutaneous manifestations of SARS-CoV-2 infection and investigate their duration and timing in relation to other COVID-19 symptoms.

Methods: We used data from 336 847 UK users of the COVID Symptom Study app to assess the diagnostic value of body rash or an acral rash in SARS-CoV-2 infection, and data from an independent online survey of 11 544 respondents to investigate skin-specific symptoms and collect their photographs.

Results: Using data from the app, we show significant association between skin rashes and a positive swab test result (odds ratio 1·67, 95% confidence interval 1·42-1·97). Strikingly, among the respondents of the independent online survey, we found that 17% of SARS-CoV-2-positive cases reported skin rashes as the first presentation, and 21% as the only clinical sign of COVID-19. Together with the British Association of Dermatologists, we have compiled a catalogue of images of the most common skin manifestations of COVID-19 from 400 individuals (https://covidskinsigns.com), which we have made publicly available to assist clinicians in recognition of this early clinical feature of COVID-19.

Conclusions: Skin rashes cluster with other COVID-19 symptoms, are predictive of a positive swab test, and occur in a significant number of cases, either alone or before other classical symptoms. Recognizing rashes is important in identifying new and earlier cases of COVID-19.

Figure 1

Study summary. We used data collected through the COVID Symptom Study app to investigate the ability of cutaneous symptoms to identify SARS‐CoV‐2 infection (Phase 1). An independent online survey was used to collect skin‐specific symptoms in order to explore their presentation, duration and timing in relation to other COVID‐19 symptoms, and to collect photographs of skin symptoms (Phase 2). Light‐coloured rectangles highlight the data used in the analyses; dark‐coloured rectangles represent the observations generated by this study; and the rectangles at the bottom summarize the main findings. CI, confidence interval; OR, odds ratio; QC, quality control.

Figure 2

Example of COVID‐19‐related cutaneous manifestations. (a) Papular rash. Top: erythematopapular rash on the back. Bottom: erythematopapular eruption on the forearm; some blistering and necrosis of the top layers of the epidermis is also visible. (b) Urticarial rash. Top: large urticated plaques on the back of the thighs and popliteal fossae. Bottom: widespread urticaria on the torso. (c) Acral rash. Top: erythema on the dorsal aspect of the second and third toes with a blister on the second toe. Bottom: erythematous annular lesions with some shedding of the epidermis on the fingers and palms. (d) Vasculitic body. Top: petechiae on the dorsum of the foot. Bottom: multiple petechiae with blood cell extravasation on the calf. (e) Livedo reticularis. Top: livedo reticularis on the arm. Bottom: livedo reticularis on the thigh.

Figure 3

Duration of symptoms. Distribution of symptom duration is shown for the three most common cutaneous symptoms diagnosed from the selected photographs. P‐values were generated via Wilcoxon’s test.