Histopathological Spectrum of Cutaneous Reactions following COVID-19 Vaccine - An Observational Study.

Background: Owing to the myriad clinical presentations of COVID-19 vaccine-induced adverse events, clinicopathological correlation is the key to understanding the underlying pathophysiology of these reactions. However, there is still a dearth of such systematic studies across a wide spectrum of vaccine reactions. Aim and Objectives: This study provides a clinical and histopathological correlation of COVID-19 vaccine-induced mucocutaneous reactions. Materials and Methods: The study population included all the individuals developing any form of self-reported mucocutaneous adverse events within 4 weeks of receiving the COVID-19 vaccine. The clinical and histopathological features were recorded. Results: A total of 126 cases were identified. Seven histopathological patterns were recognized. The most common histopathological feature was spongiotic dermatitis, seen in all the patients with "vaccine-related eruption of papules and plaques" (VREPP). Other patterns included lichenoid or interface dermatitis, dermal hypersensitivity reaction, leukocytoclastic vasculitis, subepidermal blistering, psoriasiform hyperplasia, and dermal granulomatous reaction. Conclusion: Owing to such myriad clinical presentations, utilizing a histopathological classification could ease categorizing the vaccine-induced mucocutaneous eruptions.