Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2022;12(3):e2022109 1 Dermatology Practical & Conceptual A Pink Nodule With White Halo: Dermoscopy of Halo Melanoma Francesco Borgia1, Luca Di Bartolomeo1, Marialorena Coppola1, Maria Lentini2, Elvira Moscarella3, Mario Vaccaro1 1 Section of Dermatology, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy. 2 Department of Human Pathology in Adult and Developmental Age “Gaetano Barresi”, University of Messina, Messina, Italy. 3 Dermatology Unit, University of Campania “L. Vanvitelli”, Naples, Italy. Keywords: melanoma, dermoscopy, halo nevus, amelanotic melanoma Citation: Borgia F, Di Bartolomeo L, Coppola M, Lentini M, Moscarella E, Vaccaro M. A pink nodule with white halo: dermoscopy of halo melanoma. Dermatol Pract Concept. 2022;12(3):e2022109. DOI: https://doi.org/10.5826/dpc.1203a109 Accepted: November 8, 2021; Published: July 2022 Copyright: ©2022 Borgia et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 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: Luca Di Bartolomeo, MD. Department of Clinical and Experimental Medicine, University Hospital G. Martino, via Consolare Valeria, 98125 Messina, Italy. E-mail: lucadibartolomeo@live.it Introduction Halo phenomenon consists in an area of depigmentation around a skin lesion. It represents a benign regression phe- nomenon most associated with acquired nevi [1]. Very rarely, a hypopigmented halo can also occur around melanomas (halo melanoma, HM). Dermoscopy may help to distinguish them from common halo nevi (HN). Case presentation We report the case of a 63-year-old man with a nodular, amel- anotic lesion on the back surrounded by an achromic halo. The patient reported that the lesion occurred 1 year before, with a progressive increase in size during the last 5 months. The lesion had become itchy, developing a vitiligo-like halo. Physical examination showed a symmetrical, reddish nodule, 8 mm in diameter, surrounded by a whitish area of about 2.5 cm x 2 cm. No other areas of depigmentation were detected on total body examination (Figure 1, A and B). Dermoscopy revealed central whitish and blue areas on a homogeneous pink-red background and polymorphous vascular pattern characterized by arborizing, hairpin and linear irregular ves- sels, mainly arranged at the periphery. No pigment network was detected (Figure 1, C and D). Histology showed achro- mic atypical melanocytes aggregated in the dermis, without epidermotropism (Figure 2A). A perilesional lymphocytic infiltration with fibrosis at the periphery of the nodule was observed. Immunohistochemical analysis was positive for melanocytic markers but did not show basal melanocytes in the area of epidermidis surrounding the nodule (Figure 2B). Total-body positron emission tomography scan results were unremarkable. The diagnosis of dermal melanoma was fi- nally made (Breslow thickness 2.4 mm, non-ulcerated). Wider local excision and sentinel node biopsies were neg- ative. The patient was disease free at 12 months follow-up. 2 Research Letter | Dermatol Pract Concept. 2022;12(3):e2022109 Figure 1. (A) Clinical overview of the patient. (B) Naked-eye appearance of amelanotic halo melanoma as a reddish papule surrounded by an achromic halo. (C) Dermoscopy showed central whitish and blue areas on a homogeneous pink-red background and polymorphous vascular pattern. (D) Close-up of dermoscopic view. Figure 2. (A) Dermal proliferation of atypical achromic melanocytes with nodular dermal expansion and collarette formation at the periphery (H&E, 4x). (B) Immunohistochemistry supports the melanocytic phenotype and emphasizes the lack of junctional melanocytes in the epidermis straddling the collarette (HMB45 immunostaining with hematoxylin counterstain, 4x). Conclusions HN occurs in about 1% of the general population while HM is rarer, with only few cases reported in literature [1]. Both HN and HM appear as a melanocytic lesion surrounded by a rim of white halo. The main distinguishing clinical feature is that the shape of the achromic halo tends to be more asymmetric in HM compared to HN [1]. HM also Research Letter | Dermatol Pract Concept. 2022;12(3):e2022109 3 seems to occur at older age. There are only a few reports dealing with dermoscopy of HM, characterized by mela- noma-specific multicomponent patterns with atypical pig- mented network, irregular dots/globules, streaks, blotches, blue-white veil and atypical vascular structures [2]. In our patient the absence of the pigmentary network and the polymorphous vessels in asymmetric arrangement did not allow to rule out cutaneous melanoma metastasis, even if hypopigmented peripheral halo has been very rarely re- ported in such cases [1]. Histology did not highlight pri- mary melanoma criteria, as ulceration, intraepidermal component, presence of associated nevus or regression. However, the absence of primitive melanoma in another site, as revealed by instrumental exams, led us to conclude for the diagnosis of primary dermal melanoma with peri- tumoral achromic halo. HM is the most worrisome differential diagnosis of HN. In most cases, dermoscopy may provide useful additional in- formation to clinical assessment, especially about the vascu- lar pattern. However surgical excision and histopathological examination are mandatory especially in case of achromic nodular lesion like in our patient. References 1. Nedelcu RI, Zurac SA, Brînzea A, et al. Morphological features of melanocytic tumors with depigmented halo: review of the lit- erature and personal results. Rom J Morphol Embryol. 2015;56 (2 Suppl):659-663. PMID: 26429156. 2. Conforti C, Zelin E, Dri A, et al. Hypomelanotic halo melanoma: dermoscopic findings. Ital J Dermatol Venerol. 2021;156(3):408- 409. DOI: 10.23736/S0392-0488.20.06727-9. PMID: 33084271.