Dermatology: Practical and Conceptual Letter | Dermatol Pract Concept 2018;8(4):11 303 DERMATOLOGY PRACTICAL & CONCEPTUAL www.derm101.com Introduction Reactive perforating collagenosis (RPC) is a rare disorder in which abnormal collagen fibers extrude through the epider- mis. In the acquired form, erythematous keratotic papules and plaques with firmly adherent central crust and ulceration develop, commonly on the trunk and extremity extensor surfaces, and often at sites of superficial trauma [1]. Intense itch is common. Acquired RPC is often associated with long- standing diabetes and chronic renal failure, particularly in patients undergoing dialysis [2,3]. However, because RPC is uncommon, the clinical presen- tation can vary between patients, and it can be difficult to differentiate clinically from other conditions, the true diagno- sis is often missed or delayed. Differential diagnosis includes ecthyma, prurigo nodularis, perforating granuloma annulare, dermatitis artefacta, and other perforating diseases [4]. Clini- cal diagnosis of RPC is supported or confirmed by charac- teristic histopathological features in most cases, although repeated biopsies may be required. Histological features vary according to stage of disease; in the early stages degenerate collagen fibers accumulate in dermal papillae and epidermal hyperplasia may be seen. In more established lesions a cup- shaped depression of the epidermis develops with an overlying keratin plug containing inflammatory cells, keratinous debris, and collagen fibers [4,5]. Vertically oriented collagen fibers, stained red by elastic van Gieson staining or blue by Masson’s trichrome stain, are extruded through the epidermis and there may be a mild perivascular lymphohistiocytic infiltrate. Dermoscopy is a noninvasive technique which is now a standard tool used in the preoperative clinical diagnosis of skin tumors [6]. It is also increasingly used to aid in the diagnosis in other dermatological conditions including inflammatory dermatoses [7,8]. To our knowledge, the der- moscopic features of RPC have been described in 2 previous case reports [9,10]. Here we report the dermoscopic findings in a series of 5 patients with RPC. Case Presentations We identified 5 patients with a diagnosis of acquired RPC in our department over the past 2 years. Case notes, pathology Dermoscopy features of acquired reactive perforating collagenosis: a case series Emma Ormerod1, Ausama Atwan2, Laszlo Intzedy3, Natalie Stone2 1 Dermatology Department, Bristol Royal Infirmary, Bristol, UK 2 Dermatology Department, Royal Gwent Hospital, Newport, Wales, UK 3 Pathology Department, Royal Gwent Hospital, Newport, Wales, UK Key words: dermoscopy, perforating collagenosis, acquired, diagnostics Citation: Ormerod E, Atwan A, Intzedy L, Stone N. Dermoscopy features of acquired reactive perforating collagenosis: a case series. Dermatol Pract Concept. 2018;8(4):303-305. DOI: https://doi.org/10.5826/dpc.0804a11 Received: December 4, 2017; Accepted: April 20, 2018; Published: October 31, 2018 Copyright: ©2018 Ormerod et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: None. Competing interests: The authors have no conflicts of interest to disclose. All authors have contributed significantly to this publication. Corresponding author: Emma Ormerod, MA, MRCP, Bristol Dermatology Unit, Bristol Royal Infirmary, Marlborough Street, Bristol BS2 8HW. Email: Emma.ormerod@uhbristol.nhs.uk 304 Letter | Dermatol Pract Concept 2018;8(4):11 onset of his skin problems; he subsequently started a regi- men of low molecular weight heparin. Routine blood values, including renal function, were normal. Skin biopsy showed ulceration of epidermis, acute and chronic inflammation at the ulcer base with leukocytoclasis, and a perivascular chronic inflammatory infiltrate in the mid-dermis. Patient 3. A 58-year-old man with a previous diagnosis of sarcoidosis was taking no regular medications. Routine blood values at the time of presentation were normal. Skin biopsy from an ulcer showed florid reactive changes and vertically oriented collagen fibers at the ulcer base consistent with RPC. Renal function was normal. Patient 4. An 83-year-old woman was housebound and unable to attend the dermatology clinic. She was referred via teledermatology for review of her images and clinical history. She had a history of an aortic aneurysm, hypertension, atrial fibrillation, and transient ischemic attack. Blood tests revealed microcytic anemia but normal renal function. Biopsy was not felt to be appropriate for this patient; the diagnosis was made from classic clinical and dermoscopy features. Patient 5. An 80-year-old woman had a history of long- standing type 2 diabetes mellitus, ischemic heart disease, and hypertension. Medications included lercanidipine, furosemide, reports, and dermoscopy pictures were analyzed. Dermo- scopic images were taken using a digital dermoscopy system (Nikon D33S camera [Nikon, Tokyo, Japan]; Heine Delta® 20T Dermatoscope [Heine Optotechnik, Herrsching, Ger- many]). Minimal pressure was applied and ultrasound gel was used during the process to help preserve vessel morphology as much as possible. There were 3 female and 2 male patients, with age rang- ing from 53 to 83 years. All of them gave a history of a very itchy rash, affecting the trunk and/or lower limbs. The rash had a similar appearance in all patients, with erythematous nodules of varying sizes and central keratin plug (Figure 1). The diagnosis of RPC was suspected clinically in all patients and confirmed histologically in 4 of the 5 cases (in 1 patient, biopsy was felt to be inappropriate). Patient 1. A 53-year-old woman had a 20-year history of type 2 diabetes mellitus, peripheral vascular disease, and ischemic heart disease. Her medications included metformin, clopidogrel, bisoprolol, and lisinopril. Routine blood values, including renal function, were normal, and skin biopsy was consistent with RPC, showing vertical collagen orientation. Patient 2. A 67-year-old man was diagnosed with bilateral pulmonary embolism at approximately the same time as the Figure 2. Dermoscopic images of a typical lesion from the rash in each of the 5 patients (patients 1-5, labeled A-E). [Copyright: ©2018 Ormer- od et al.] Figure 1. Macroscopic images of the rash in each of the 5 patients (patients 1-5, labeled A-E). [Copyright: ©2018 Ormerod et al.] Letter | Dermatol Pract Concept 2018;8(4):11 305 References 1. Millard PR, Young E, Harrison DE, Wojnarowska F. Reactive perforating collagenosis: light, ultrastructural and immunohisto- logical studies. Histopathology. 1986;10:1047-1056. 2. Morton CA, Henderson IS, Jones MC, Lowe JG. Acquired perfo- rating dermatosis in a British dialysis population. Br J Dermatol. 1996;135:671-677. 3. Poliak SC, Lebwohl MG, Parris A, Prioleau PG. Reactive perforat- ing collagenosis associated with diabetes mellitus. N Engl J Med. 1982;306:81-84. 4. Kim SW, Kim MS, Lee JH, et al. A clinicopathologic study of thirty cases of acquired perforating dermatosis in Korea. Ann Dermatol. 2014;26:162-171. 5. Cerio R, Calnan CD, Wilson-Jones E. A clinic-pathological study of reactive perforating collagenosis: report of 10 cases. Br J Der- matol. 1987;117:16-17. 6. Argenziano G, Soyer HP, Chimenti S, et al. Dermoscopy of pigmented skin lesions: results of a consensus meeting via the internet. J Am Acad Dermatol. 2003;48:679–693. 7. Goncharova Y, Attia EA, Souid K, Protzenko O, Koktishev I. Dermoscopic features of clinically inflammatory dermatoses and their correlation with histopathologic reaction patterns. Arch Dermatol Res. 2015;307:23-30. 8. Lallas A, Kyrgidis A, Tzellos TG, et al. Accuracy of dermoscopic criteria for the diagnosis of psoriasis, dermatitis, lichen planus and pityriasis rosea. Br J Dermatol. 2012;166:1198-1205. 9. Kittisak P, Tanaka M. Dermoscopic findings in a case of reactive perforating collagenosis. Dermatol Pract Concept. 2015;5:75-77. 10. Ramirez-Fort MK, Khan F, Rosendahl CO, Mercer SE, Shin-Chang H, Levitt JO. Acquired perforating dermatosis: a clinical and der- matoscopic correlation. Dermatol Online J. 2013;19:18958. nicorandil, candesartan, and atenolol. Blood values were nor- mal apart from an elevated HbA1c in keeping with her known diabetes. Histology showed focal necrosis, ulceration and epidermal inflammation, with perivascular chronic inflamma- tory cell infiltrate in the dermis. Dermoscopic images showed almost identical features in all 5 patients (Figure 2). The 3 clear, consistent features were (1) a yellow-brown structureless area in the center of the lesion in keeping with surface crust; (2) a white rim surrounding the crust which can vary in thickness between patients and in a single lesion, possibly correlating to epidermal invagination or keratinous debris; and (3) an outer pink circle of inflammation with visible vessels, commonly short looped vessels centrally and dotted vessels peripherally. These features are similar to those previously described in 2 separate reports of single cases with RPC [9,10]. Conclusions RPC is an unusual condition that can mimic other conditions and is often initially misdiagnosed. The dermoscopic find- ings in our cases reinforce the features described in previous reports [9,10] and indicate that dermoscopy in RPC gives a very characteristic, consistent appearance and can therefore be a useful and quick aid to make the diagnosis. Dermoscopy of RPC is particularly helpful in cases in which biopsy is not possible or is nondiagnostic.