We report a case of a 72-year-old man who underwent surgical excision of a keratoacanthoma centrifugum marginatum (KCM) located on the left forearm. It is an uncommon variant of keratoacanthoma, which can assume large dimensions (up to 20 cm) and does not tend to spontaneous regression. The lesion is usually single, with raised borders, and has progressive centrifugal growth associated with central healing and atrophy. Due to its rarity and lack of pathognomonic histopathological features, KCM can be a diagnostic challenge for dermatologists and pathologists.

Keywords: Keratoacanthoma; Neoplasms; Skin neoplasms

Persistent Intermittent Delayed Swelling (PIDS) is an immune-mediated inflammatory reaction resulting from the interaction of immunological factors and the product's intrinsic characteristics. Such a reaction generally occurs after 30 days and persists while hyaluronic acid (HA) is in the area. We present through this case report a PIDS-type reaction that occurred five years after the injection of the product.

Keywords: Foreign body reaction; Dermal fillers; Hyaluronic acid