Bullous pemphigoid with secondary acquired reactive perforating collagenosis: a challenging clinical case report

Bullous pemphigoid (BP) is a common autoimmune blistering disorder with unknown aetiology. During the last decades, its association with various common comorbidities, including cardiovascular, metabolic, neuropsychiatric, and neoplastic disorders, has been established. However, in recent years, an increasing number of BP cases have also been reported in association with rarer diseases, including acquired reactive perforating collagenosis (ARPC). Patients with coexisting BP and ARPC have been reported to share common clinical features, including metabolic comorbidities, e.g., diabetes mellitus (DM). As the evolution from ARPC cutaneous involvement to classic BP lesions has been more frequently described, it has been suggested that it may represent a new clinical variant of BP with a specific pathogenetic background. Here is reported a challenging case in which a typical onset of BP was later followed by the eruption of atypical ARPC lesions in a patient with multiple non-compensated metabolic and cardiovascular comorbidities.