An old entity, a new trigger: Post COVID-19 vaccine Pityriasis rubra pilaris.

Background Pityriasis rubra pilaris (PRP) is a rare, acquired, chronic papulosquamous dermatosis which can occur in all ages. PRP can be associated with infection, autoimmunity, drugs and malignancies, and can be idiopathic. Objective PRP following vaccination has been rarely described in the literature. To the best of our knowledge, we report the first case of PRP two weeks following COVID-19 vaccination (Covishield). Case report A 72-year-old male presented to the outpatient dermatology department at All India Institute of Medical Sciences - Bhopal with minimally pruritic superficial plaques since one week. The patient was vaccinated against COVID-19 with Covishield two weeks earlier. The lesions developed as erythematous scaly follicular papules and plaques over axilla that rapidly spread to the trunk in the following weeks and involved palms and soles as well as thickening and fissuring. The clinical features suggested PRP. The histopathology showed epidermal acanthosis with hypergranulosis alternating with parakeratosis and orthokeratosis with broad rete ridges with follicular plugging. The patient had started taking topical corticosteroids and emollients, which proved effective. There was no recurrence after receiving a second dose on follow-up. Conclusion In patients presenting with new onset PRP in this COVID-19 era, the possibility of vaccine as a trigger should be taken into consideration, and further dosing should be carefully monitored in view of possible recurrence.