Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2025;15(1):4709 1 Perianal Plasma Cell Dermatitis: A Diagnostic Challenge with Unique Dermatoscopic Features Gunel Rasulova1, Seçil Vural1, Sümeyre Seda Ertekin1, Cuyan Demirkesen2, Bengü Nisa Akay3 1 Department of Dermatology, Faculty of Medicine, Koc University Hospital, Istanbul, Turkey 2 Department of Pathology, Faculty of Medicine, Acibadem University, Istanbul, Turkey 3 Department of Dermatology, Faculty of Medicine, Ankara University, Ankara, Turkey Key words: Plasma cell dermatitis, dermatoscopy, perianal lesion, Zoon balanitis, Inflammoscopy adenoma Citation: Rasulova G, Vural S, Ertekin SS, Demirkesen C, Akay BN. Perianal Plasma Cell Dermatitis: A Diagnostic Challenge With Unique Dermatoscopic Features. Dermatol Pract Concept. 2025;15(1):4709. DOI: https://doi.org/10.5826/dpc.1501a4709 Accepted: September 28, 2024; Published: January 2025 Copyright: ©2024 Rasulova et al. This is an open-access article distributed under the terms of the Creative Commons Attribution- Noncommercial License (BY-NC-4.0), https://creativecommons.org/licenses/by-nc/4.0/, which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original authors and source are credited. Funding: None. Competing Interests: None. Authorship: All authors have contributed significantly to this publication. Corresponding Author: Gunel Rasulova, Department of Dermatology, Faculty of Medicine, Koc University Hospital, Istanbul, Turkiye, Koc University Hospital, Maltepe Mahallesi, Davutpaşa Caddesi, No:4 Topkapı, 34010 Istanbul / Türkiye; Phone: +90212 467 87 00; E-mail: gunelrasul@gmail.com Introduction Perianal plasma cell dermatitis is a rare condition charac- terized by inflammatory perianal lesions. Diagnosis can be challenging due to overlapping clinical features with other conditions. We present a case highlighting the diagnostic util- ity of dermoscopy in perianal lesions, with unique findings. Case Presentation A 37-year-old woman with a history of kidney trans- plantation presented with perianal lesions that had been persisting for 1 month. Physical examination revealed 3 well- demarcated, erythematous, shiny, erosive plaques and a papule in the perianal region (Figure 1A). Dermoscopic examination showed pink-orange structureless areas with polymorphic vessels, including elongated coiled vessels and vessels with central dots within a circle. The vessels were mainly arranged in lines. There were clustered gray dots/ clods at the base of the lesion (Figure 1B). The patient’s syphilis serology returned negative. Histo- pathological analysis of a punch biopsy confirmed plasma cell mucositis (Figure 2, A and B). Treatment with fusidic acid 2% and betamethasone valerate 0.1% cream resulted in partial regression of lesions after 1 month. Conclusions Plasma cell mucositis, originally described as Zoon balanitis, is a rare inflammatory condition primarily affecting muco- sal surfaces [1]. While its non-mucosal counterpart has been reported in various locations, including the perianal region, its presentation and diagnosis remain challenging [2]. Our case adds to the limited literature on perianal plasma cell dermatitis, emphasizing the importance of recognizing its dermoscopic features to facilitate accurate diagnosis. 2 Research Letter | Dermatol Pract Concept. 2025;15(1):4709 Dermoscopy plays a crucial role in diagnosing perianal plaques, since the dermoscopic features of Zoon balanitis are well-established. These features include pink-orange struc- tureless areas, linear curved vessels of serpentine, convoluted, chalice-shaped morphologies, linear vessels distributed in an irregular pattern, and dotted/glomerular vessels that are usu- ally sparse in distribution [3]. Given the overlapping clinical features with conditions like Bowen disease, erythroplasia of Queyrat, and extramammary Paget disease, dermoscopy offers a valuable means of differentiation [4,5]. The dermoscopic examination of our case closely mir- rored the characteristic features of Zoon balanitis, present- ing pink-orange structureless areas accompanied by linear, curved, and elongated coiled vessels. Notably, the elongated and enlarged coiled vessels observed resembled those typi- cally associated with Bowen disease, adding complexity to the differential diagnosis. Additionally, the identification of vessels exhibiting a central dot within a circle represents a novel finding, suggesting potential variations in the dermo- scopic presentation of plasma cell dermatitis. These observa- tions emphasize the need for further studies to explore the diagnostic utility of dermoscopy across different anatomical locations. Ultimately, our report underscores the invaluable role of dermoscopy as a non-invasive diagnostic tool in the evaluation of perianal plaques, facilitating accurate diagno- sis and appropriate management strategies. Figure 1. (A) Clinical image of the patient’s perianal area. (B) Dermoscopic features of the lesion. Pink-orange structureless area with clustered gray dots/clods at the base of the lesion (circle) and polymorphic vessels including looped (blue arrowhead), curved (white arrowhead), elongated large coiled (blue arrow), serpentine (black arrowhead), and vessels presenting with central dot within a circle (black arrow). Research Letter | Dermatol Pract Concept. 2025;15(1):4709 3 References 1. Weyers W, Ende Y, Schalla W, Diaz-Cascajo C. Balanitis of Zoon: a clinicopathologic study of 45 cases. Am J Dermatopathol. 2002 Dec;24(6):459-467. DOI: 10.1097/00000372-200212000- 00001. PMID: 12454596. 2. Mitkov M, Pimentel J, Bruce A. Beefy red plaques in the perianal region. JAMA Dermatol. 2014 Apr;150(4):447-8. DOI: 10.1001 /jamadermatol.2013.7639. PMID: 24553775. 3. Errichetti E, Lacarrubba F, Micali G, Stinco G. Dermoscopy of Zoon’s plasma cell balanitis. J Eur Acad Dermatol Venereol. 2016 Dec;30(12):e209-e210. DOI: 10.1111/jdv.13538. Epub 2015 Dec 15. PMID: 26670716. 4. Errichetti E, Lallas A, Di Stefani A, et al. Accuracy of dermoscopy in distinguishing erythroplasia of Queyrat from common forms of chronic balanitis: results from a multicentric observational study. J Eur Acad Dermatol Venereol. 2019 May;33(5):966-972. DOI: 10.1111/jdv.15443. PMID: 30350374. 5. Bayan CY, Khanna T, Rotemberg V, Samie FH, Zeitouni NC. A review of non-invasive imaging in extramammary Paget’s disease. J Eur Acad Dermatol Venereol. 2018 Nov;32(11): 1862-1873. DOI: 10.1111/jdv.15052. PMID: 29906363. Figure 2. (A) Prominent dermal inflammatory cell infiltration, underneath an acanthotic and spongiotic epidermis, displaying findings of excoriation on the surface (H&E, ×16). (B) Inflammatory cell infiltration, rich in plasma cells (×40).