Background <p>Calciphylaxis, also termed calcific uremic arteriolopathy (CUA), is a rare and potentially fatal vasculopathic disorder predominantly affecting patients with end-stage kidney disease (ESKD), particularly those undergoing dialysis or who have recently received kidney transplantation. The hallmark histopathological features of CUA encompass medial calcification of systemic arterioles, intimal fibrosis, and thrombosis. In contrast, Acquired Reactive Perforating Collagenosis (ARPC), a rare perforating dermatosis frequently associated with systemic diseases, is characterized by the transcutaneous elimination of degenerated dermal collagen fibers through the epidermis. Despite the clinical resemblance of cutaneous lesions between CUA and ARPC, their therapeutic approaches differ substantially. Misdiagnosis may result in delayed appropriate treatment and consequently poor prognosis.</p> Case presentation <p>This report describes three cases of ARPC that were initially misdiagnosed as CUA at external institutions.</p> Conclusions <p>This report aims to provide clinicians with valuable insights to enhance the accurate diagnosis and optimal management of these two distinct conditions.</p> Clinical trial number <p>Not applicable.</p>