Dermoscopy of a Congenital Pigmented Lesion: A Case of Supernumerary Nipple

A 20-year-old man presented with an asymptomatic pigmented lesion on the left side of the chest. The lesion was present since birth, with an increase in size in proportion to the growth of the body. There were no similar lesions on the rest of the body. There was no history of hair growth, bleeding, ulceration, or any discharge from the lesion. On examination, a brown-black, well-defined plaque measuring approximately 1.5 × 1.5 cm, with a wrinkled surface and central depression observed. The plaque was located 7 cm below and 3 cm medial to the left nipple along the milk line [Figure 1]. On dermoscopy, there was a central whitish, scar-like structure with a cleft, along with a few cobblestone-like globules, and peripheral network-like structures [Figure 2 and Supplementary Figure 1], suggestive of a supernumerary nipple (SNN).Figure 1: Clinical image of the patient showing a brown to black, well-defined plaque measuring approximately 1.5 × 1.5 cm with a wrinkled and central depressed surface, below the left nippleFigure 2: Dermoscopic image (DermLite DL4, Polarized mode, 10×) showing a central whitish scar-like structure with a cleft (red arrow), few cobblestone-like globules (blue arrow), and peripheral network-like structures (green arrow)SNN represents a developmental anomaly that most often arises along the embryonic milk lines, predominantly on the anterior aspect of the trunk, with a noted predilection for the left side.[1] Dermoscopy serves as a valuable noninvasive tool for identifying SNN. The characteristic dermoscopic hallmark of SNN is the coexistence of a peripheral network-like pigment pattern with a white scar-like area, observed in more than 80–90% of reported SNN cases.[2] This peripheral network, resembling a pigment network, may misleadingly suggest a melanocytic lesion; however, it represents a nonmelanocytic structure specific to accessory nipple tissue. Additional dermoscopic features of SNN include white cobblestone-like globules, cleft-like depressions, central dimpling with a keratin plug, and comedo-like openings. Although these features occur variably, they may significantly aid in diagnosis, especially in atypical presentations. Differential diagnoses of SNN include dermatofibroma, melanocytic nevus, pigmented basal cell carcinoma, and rarely melanoma. Dermoscopy of dermatofibroma shows a central white patch without a cleft, alongside a delicate peripheral pigment network, and lacks lobulated globules.[3] Melanocytic nevi show a true pigment network rather than the pseudonetwork seen in SNN. Pigmented basal cell carcinoma demonstrates arborizing vessels, blue–gray ovoid nests, and shiny white structures.[3] Histopathologically, the cobblestone-like globules correspond to lobulated adnexal and glandular structures within accessory nipple tissue, the white scar-like area corresponds to underlying fibrous stroma, and the central cleft-like depression represents the rudimentary nipple sulcus.[2,4] Recognizing these dermoscopic signatures helps prevent misdiagnosis and unnecessary excisions for presumed melanocytic or fibrohistiocytic tumors. Authors’ contributions We confirm that all authors have read and approved the manuscript for submission. All authors meet authorship criteria, and the manuscript represents honest work. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initials will not be published and due efforts will be made to conceal his identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest One of the authors is a member of the editorial board of the journal. The manuscript was subject to journal’s standard procedure and peer review was held independently of the editor or their research group. Use of artificial intelligence (AI) The preparation of this manuscript was carried out entirely by the authors without the use of artificial intelligence technologies.Supplementary Figure 1: Dry polarised dermoscopy (DermLite DL4, 10x)