Dermatology: Practical and Conceptual Image Letter | Dermatol Pract Concept. 2024;14(2):e2024111 1 Porokeratosis Ptychotropica Mimicking Anogenital Warts Tugba Kevser Uzuncakmak1, Necmettin Akdeniz1,2, Pembe Gül Güneş3 1 Memorial Healthgroup, Sisli Hospital, Department of Dermatology, Istanbul, Turkey 2 Memorial Healthgroup, Atasehir Hospital, Department of Dermatology, Istanbul, Turkey 3 Memorial Healthgroup, Sisli Hospital, Department of Pathology, Istanbul, Turkey Citation: Uzuncakmak TK, Akdeniz N, Güneş PG. Porokeratosis Ptychotropica Mimicking Anogenital Warts. Dermatol Pract Concept. 2024;14(2):e2024111. DOI: https://doi.org/10.5826/dpc.1402a111 Accepted: December 14, 2023; Published: April 2024 Copyright: ©2024 Uzuncakmak 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: Dr Tugba Kevser Uzuncakmak, MD, Memorial Healthgroup, Sisli Hospital, Department of Dermatology, Istanbul, Turkey . Telephone: 0 +90- (530) 6640226 E-mail: tugbakevser@gmail.com Case Presentation A 34-year-old male presented with a 7-year history of slowly increasing, multiple 3–4 mm, papular lesions on the bilateral gluteal region (Figure 1A). He had been di- agnosed with genital wart and lichen simplex chronicus previously, and topical therapies, including topical corti- costeroids, 5-FU, podophyllotoxin, and cryotherapy, had been offered to him; he stated that he had had no benefit from previous treatments. In dermoscopic examination, sharply demarcated hyperpigmented hyperkeratotic pe- ripheral rim with a light brown hyperpigmentation, center with yellowish and whitish scales, and white structureless areas were detected (Figure 1B-1C). Histologically, irregu- lar acanthosis, and cornoid lamella formation in the areas of epidermal invagination were observed in the epidermis. The cornoid lamella structures were composed of dysker- atotic cells with granular layer loss and vacuoles under the parakeratotic column. Vacuolar degeneration was observed at the dermo-epidermal junction, and perivascu- lar lymphocyte infiltration was observed around the di- lated capillary vessel (Figure 1D). The patient was treated with Er:YAG laser. Teaching Point Porokeratosis ptychotropica (PP) is a rare variant of poro- keratosis that is characterized by symmetrical dyskeratotic skin lesions on the gluteal clefts [1]. It was first described by Lucker et al. in 1995, and to date, few cases have been re- ported in the literature. PP may be misdiagnosed as psoriasis, eczema, epidermal nevus, candidiasis, squamous cell carci- noma, cutaneous tuberculosis, Bowen disease, or anogenital warts, as in our patient [2]. It presents clinically as a char- acteristic butterfly-shaped scaly plaque with a raised rim. These lesions are usually itchy, which may lead to scratching and chronic inflammation. Therapeutic options in the treat- ment of PP are limited and usually not curative. There are 2 Image Letter | Dermatol Pract Concept. 2024;14(2):e2024111 few case reports about various treatment options, such as topical/intralesional corticosteroids, topical/ systemic reti- noids, imiquimod, cholesterol, 5-fluorouracil, simvastatin, excimer laser, photodynamic therapy, intralesional bleomy- cin injection, cryotherapy, CO2 laser, and dermatome, and excision has been reported in the literature, but complete clearance has not been observed with almost any treatment [3,4]. In our case, focal recurrence foci were observed after ablative fractional Erbium:YAG laser treatment, although not as much as in the first visit, and follow-up with repeated laser treatments was recommended. We present this rare dis- order, which has the risk of progressing into squamous cell carcinoma in the long term if left untreated, as a reminder of the differential diagnosis of many benign and malignant anogenital dermatoses. References 1. Zaar O, Polesie S, Navarrete-Dechent C, et al. Dermoscopy of porokeratosis: results from a multicentre study of the Interna- tional Dermoscopy Society. J Eur Acad Dermatol Venereol. 2021; 35(10):2091-2096. doi:10.1111/jdv.17439 2. Lacarrubba F, Musumeci ML, Verzì AE, Poma C, Caltabiano R, Micali G. Porokeratosis Ptychotropica: Dermoscopy, Reflec- tance Confocal Microscopy, and Histopathological Correlation. Indian J Dermatol. 2021 Sep-Oct; 66 (5): 540-542. 3. Albanell-Fernández M, Luque-Luna M, López-Cabezas C, et al. Treatment of Porokeratosis Ptychotropica With a Topical Combination of Cholesterol and Simvastatin. JAMA Dermatol. 2023;159(4):458-460. doi:10.1001/jamadermatol.2022.6591 4. Ryoo YW, Kim Y, Yun JM, Kim SA. Porokeratosis ptychotropica: a case report.  J Yeungnam Med Sci. 2023;40(4):423-425. doi:10.12701/jyms.2022.00549 Figure 1. (A) Clinical presentation of itchy hyperkeratotic popular lesions on gluteal cleft (B-C) Hyperpigmented hyperkeratotic peripheral rim with a light brown hyperpigmentation, center with yellowish and whitish scales, and white structureless areas were seen at dermoscopy (D) A cornoid lamella in porokeratosis. A thin column of parakeratotic cells overlies a narrow zone in which the granular layer has disap- peared. Vacuolar degeneration was observed at the dermoepidermal junction, and perivascular lymphocyte infiltration was observed around the dilated capillary vessel in dermis (H&E, 10×10).