Bullous Pilomatricoma Arising at a BNT162b2 mRNA COVID-19 Vaccination Site / 대한피부과학회지

ABSTRACT

Pilomatricoma is a common benign tumor that originates from hair matrix cells. Bullous pilomatricoma (BP) is a rare variant that often occurs on the upper extremities. A 23-year-old male presented with a cyst on the left upper arm for 6 months. He received the BNT162b2 (Pfizer) mRNA COVID-19 vaccine in the same location approximately 6 months prior to presentation. The lesion appeared 1 week after inoculation and gradually enlarged.Physical examination revealed a 2.5-×2.0-cm-sized, pinkish cystic nodule on the left upper arm. The lesion was excised, and histopathological examination showed a well-circumscribed nodule composed of basophilic cells and eosinophilic shadow cells. Finally, the patient was diagnosed with BP. The exact cause of BP formation following vaccination is yet to be determined; however, this report presents the possibility of BP occurrence in individuals with chronic skin lesions at the site of vaccination.