Acquired Reactive Perforating Collagenosis—A Rare Entity Occurring Within Common Disorders: A Systematic Review and Our Personal Experience

<b>Background/Objectives</b>: Acquired reactive perforating collagenosis (ARPC) is a rare entity usually occurring in adults with systemic diseases such as diabetes mellitus, chronic kidney disease (CKD), cardiovascular diseases, and malignancies, although drug-related and trauma-induced cases have also been reported. Given its rarity and the lack of consensus on optimal management, we conducted a systematic review to summarize updated diagnostic and therapeutic insights into ARPC. Additionally, we report a case of ARPC associated with CKD. <b>Methods</b>: This study was conducted in accordance with the PRISMA 2020 (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A literature search was performed in the PubMed database between May-September 2025. The search strategy targeted open-access, primary human studies, published within the last 15 years, available in English, and including adult patients with histopathologically confirmed ARPC. <b>Results</b>: Twenty-seven studies, predominantly case reports and case series, were included. The mean patient age was 60.8 ± 14.4 years. Only one case occurred in the absence of comorbidities, while most subjects had underlying systemic diseases. Drug-induced cases were also described. Clinically, ARPC should be suspected in patients presenting with pruritic papules/nodules with central keratotic plugs. Additional diagnostic tools include dermoscopy and reflectance confocal microscopy. However, histopathological evidence of transepidermal elimination of altered collagen fibers is mandatory. The current treatments of ARPC include antihistamines, keratolytics, topical/intralesional/oral corticosteroids, topical/systemic retinoids, phototherapy, dupilumab and allopurinol. Other therapies have been reported across the literature, including emerging ones. <b>Conclusions</b>: Once ARPC is diagnosed, a thorough evaluation for underlying diseases, including malignancies, is essential. Clinical trials are warranted to define optimal therapeutic strategies.