Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2024;14(3):e2024188 1 Vulvar Hidradenoma Papilliferum: Clinical and Dermoscopic Features in a Case Series Noura Kalmi1, Hanane Baybay1, Souad Choukri1, Zakia Douhi1, Sara Elloudi1, Meryem Soughi1, Fatima Zahra Mernissi1 1 Department of Dermatology, University Hospital Hassan II, Fes, Morocco Key words: hidradenoma papilliferum, vulva, mammary-like gland adenoma Citation: Kalmi N, Baybay H, Choukri S, et al. Vulvar Hidradenoma Papilliferum: Clinical and Dermoscopic Features in a Case Series. Dermatol Pract Concept. 2024;14(3):e2024188. DOI: Accepted: February 20, 2024; Published: July 2024 Copyright: ©2024 Kalmi et al. This is an open-access article distributed under the terms of the Creative Commons Attribution- NonCommercial License (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 Kalmi Noura, Department of Dermatology, University Hospital Hassan II, Fes, Morocco. Phone Number: +212 633668729 Email: noura.kalmii@gmail.com Introduction Hidradenoma papilliferum (HP) is a rare benign tumor of the vulva, perineum, and perianal skin, in particular the vul- var interlabial sulcus and, much less commonly, ‘‘ectopic’’ sites. For a long time, it was thought to be a benign tumor of apocrine origin. However, several pathologists have sug- gested that HP originates from glandular tissue with eccrine and apocrine characteristics. It is clinically polymorphous. Dermoscopy may be a useful tool for diagnosis. This study aimed at describing the clinical and dermoscopic character- istics of HP in the vulva. Case Presentation This retrospective observational study included seven cases of histopathologically-proven HP consulted by our derma- tology department. The average age of the patients included in our study was 44.3 years. Six of the seven tumors arose in the interlabial sulcus. All lesions had a nodular aspect; one was polylobed, and another was ulcerated. The predominant color was red; a normal skin color was observed in the two remaining cases. Clinical onset ranged from 4 to 30 months (mean 12). Four patients were asymptomatic, one patient had mild pruritus, and another was bleeding on contact. Dermoscopy imaging was available in six cases revealing a triad of features made up of a reddish-pink background, shiny white structures (5/6 cases), and vessels: hairpin vessels in one patient, dots in one patient, telangiectasias in three patients, and irregular linear vessels in another. A bluish globule was also observed in one patient, which corresponds histologically to intra- tumoral hemorrhage. In our case series, the direct approach was sufficient for complete excision of six lesions; however, the patient who had the polylobed tumor benefited from surgical reconstruction. Histological examination showed 2 Research Letter | Dermatol Pract Concept. 2024;14(3):e2024188 Ta b le 1 . P at ie nt C ha ra ct er is ti cs a nd C lin ic al a nd D er m os co pi c A sp ec ts o f L es io ns . C as e A g e (Y ea rs ) O n se t (M o n th s) Sy m p to m s Si te Si ze ( m m ) Su rf ac e C o lo r M o rp h o lo g y D er m o sc o p ic F ea tu re s 1 24 4 N on e L ef t la bi um m aj or a 15 N on -u lc er at ed R ed W el l- ci rc um sc ri be d, lig ht r ed n od ul e Pi nk b ac kg ro un d, ir re gu la r do tt ed a nd li ne ar v es se ls , br ig ht w hi te s tr uc tu re s 2 36 3 N on e R ig ht in te rl ab ia l su lc us 12 N on -u lc er at ed R ed W el l- ci rc um sc ri be d, lig ht r ed n od ul e w it h a sh in y br ig ht p in k su rf ac e Pi nk b ac kg ro un d, s hi ny w hi te a re as , t el an gi ec ta ti c ve ss el s 3 45 30 N on e R ig ht in te rl ab ia l su lc us 12 N on -u lc er at ed R ed W el l- ci rc um sc ri be d, fir m t o to uc h w it h a sh in y pi nk s ur fa ce R ed b ac kg ro un d, s hi ny w hi te a re as , i rr eg ul ar ly ar ra ng ed s er pe nt in e ve ss el s 4 39 7 B le ed in g R ig ht in te rl ab ia l su lc us 8 ul ce ra te d re d Sm al l t um or w it h an u lc er at ed s ur fa ce bl ee di ng t o th e to uc h Pi nk b ac kg ro un d, he m or rh ag ic s uf fu si on 5 30 24 N on e R ig ht in te rl ab ia l su lc us 15 N on -u lc er at ed re d Pi nk n od ul e te nd er t o to uc h Pi nk b ac kg ro un d, s hi ny w hi te s tr uc tu re s of re ti cu la r la yo ut , d ot te d ve ss el s 6 80 12 N on e R ig ht in te rl ab ia l su lc us 10 N on -u lc er at ed Sk in - co lo re d Sm al l n od ul e w it h no rm al s ki n co lo r Pi nk b ac kg ro un d, s hi ny w hi te s tr uc tu re s ha ir pi n ve ss el s, b lu is h gl ob ul e 7 56 4 Pr ur it us V ul va a nd Pe ri ne al a re a 50 m m f or th e la rg es t N on -u lc er at ed Sk in - co lo re d Po ly lo ba te t um or o f fir m c on si st en cy t ak in g th e vu lv a an d th e pe ri - an al r eg io n N ot a va ila bl e Research Letter | Dermatol Pract Concept. 2024;14(3):e2024188 3 well-limited tumor proliferation and papillary and glandular architecture surrounded by sparse fibrous tissue. In the case where dermoscopy revealed the presence of a bluish glob- ules, histology showed an intra-tumoral hemorrhage. Table 1 summarizes patient characteristics, clinical, and dermoscopic aspects of lesions. HP is a benign tumor that occurs primarily in the vulva of Caucasian women [1]. It tends to occur most often in the fourth decade [2,3]. It is a rare, slow-growing, adnexal tu- mor mainly located in the vulvar interlabial sulcus, the most common location for mammary-like anogenital glands. HP have a good prognosis, and malignant transformation is ex- tremely rare [4]. Dermoscopic findings of HP have been poorly re- ported in the literature. A case series of seven vulvar HPs in a multiracial population has been reported, and it also showed similar dermoscopic features to our case series [1]. The majority of lesions had a triad made by a red back- ground, shiny white structures which corresponds histo- logically to fibrous tissue, and polymorphous vessels which corresponds histologically to expended vessels. Another dermoscopic feature was reported: a blue homogeneous pattern associated with peripheral, large vessels without pigmentation [1]. Considering the pitfall of clinical and dermoscopic poly- morphism, vulvar HP may mimic other benign or malignant neoplasms. The differential diagnosis includes vulvar mela- noma, syringocystadenoma papilliferum, eccrine porocarci- noma [5], squamous cell carcinoma, and nodular lesions in extramammary Paget diseas [3]. Figure 1. Case 1: (A) A well-circumscribed light red nodule; (B) pink background; irregular dotted and linear vessels; bright white structures; and (C) epithelial proliferation of tubular and acinar structures covered by a double layer of abundant ductal cells and myoepithelial cells on the outer layer. Case 2: (D) Well-circumscribed light red nodule with a shiny bright pink surface, (E) pink background, shiny white area, telangiectatic vessels; and (F) tumor proliferation is made of tubulo-papillary structures within a cystic cavity (H&E, ×40). Case 3: (G) Well-circumscribed nodule, firm to touch, with a shiny pink surface; (H) red background, shiny white area, irregularly arranged serpentine vessels; and (I) well-limited tumor proliferation, papillary and glandular architecture, surrounded by sparse fibrous tissue. Case 4: (L) Well-circumscribed nodule, firm to touch, with a shiny pink surface; (M) red background, shiny white area, irregularly arranged serpentine vessels; and (N) proliferation is made up of two cellular contingents: an epithelial component with ducts of variable size without atypical character and a connective component made of regular fibroblasts, which are not very cellular. 4 Research Letter | Dermatol Pract Concept. 2024;14(3):e2024188 Cases J. 2008;1(1):282. Published 2008 Oct 29. doi:10.1186 /1757-1626-1-282 3. Baker GM, Selim MA, Hoang MP. Vulvar adnexal lesions: a 32-year, single-institution review from Massachusetts General Hospital. Arch Pathol Lab Med. 2013;137(9):1237-1246. doi:10.5858 /arpa.2012-0434-OA 4. Kambil SM, Bhat RM, D’Souza DC. Hidradenoma papilliferum of the vulva.  Indian Dermatol Online J. 2014;5(4):523-524. doi:10.4103/2229-5178.142541. 5. Val-Bernal JF, Hermana S. Vulvar eccrine porocarcinoma: report of a case and literature review. Rom J Morphol Embryol. 2017;58(4):1611-1616. Conclusion HP is clinically polymorphous, mimicking other benign or malignant neoformations, so histological examination is necessary to confirm the diagnosis and provide treatment. References 1. Tosti G, Salvini C, Barisani A, et al. Vulval hidradenoma papilliferum: a clinical and dermoscopic study.  Clin Exp Dermatol. 2020;45(8):1035-1039. doi:10.1111/ced.14254 2. Docimo S Jr, Shon W, Elkowitz DE. Bartholin’s abscess arising within hidradenoma papilliferum of the vulva: a case report. Figure 2. Case 5: (A) Pink nodule of the right interlabial sulcus; (B) pink background, shiny white structures of reticular layout, dotted vessels. Case 6: (C) Small nodule with normal skin color;(D) pink background, shiny white structures, hairpin vessels, bluish globules. Case 7: (E) Polylobate tumor of firm consistency taking the vulva and the perianal region; (F) clinical photo after reconstructive surgery; and (G, H) proliferation has 2 cellular components: an epithelial one with ducts of variable size without atypical character and another conjunc- tive one made of regular fibroblasts (magnification ×100x, ×400).