Background: Dermatoscopy is a noninvasive diagnostic tool for pigmented lesions. However, data regarding dermatoscopic features in melasma and Hori's nevus, which are commonly found in Asian populations, are still lacking. In addition, melasma coexisting with Hori's nevus presents a particular diagnostic challenge and they generally require different treatments.
Objective: We sought to describe the dermatoscopic features of melasma and Hori's nevus and to establish diagnostic clues for each condition.
Methods: Fifty patients with melasma and 46 patients with Hori's nevus were enrolled in the study. Dermatoscopic pictures were taken with Dermlite DL200 HR (3Gen, San Juan Capistrano, Califorinia) and evaluated by two blinded board-certified dermatologists.
Results: The dermatoscopic features more prominently seen in melasma compared to Hori's nevus include light brown pigmentation (98% vs. 10.9%, P<0.001), regular pigment network (38% vs. 2.2%, P<0.001), irregular pigment network (98% vs. 63%, P<0.001), arcuate structure (68% vs. 13%, P<0.001), circles (48% vs. 10.9%, P<0.001), sparing of follicles and sweat gland openings (98% vs. 4.3%, P<0.001), and telangiectasias (52% vs. 19.6%, P=0.001). In contrast, the common features of Hori's nevus include blue-brown or grey pigmentation (63% vs. 0%, P=0.001) and speckled homogenous pattern (52.2% vs. 0%, P<0.001).
Conclusion: Dermatoscopy is a useful diagnostic tool for distinguishing between melasma and Hori's nevus. In patients with coexistence of both conditions, dermatoscopy can be used to confirm the diagnosis and aid the proper treatment.
Keywords: Acquired bilateral nevus of Ota-like macules; Hori’s nevus; chloasma; dermoscopy; hyperpigmentation.
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