Abstract
Background
A melanoacanthoma (MA) is a pigmented variant of seborrheic keratosis. Owing to the pigmentation, MAs may mimic the clinical appearance of malignant melanomas (MMs). However, the dermoscopic patterns of MAs and MA-like MMs have rarely been compared.
Objective
To elucidate the clinical and dermoscopic differences between MAs and MA-like MMs.
Methods
This study included 77 MA and 33 MA-like MM patients. We retrospectively reviewed the medical records, clinical findings, and dermoscopic findings of the two groups.
Results
Crypts and comedo-like openings (71.4%) in MAs and the blue-white veil (60.6%) in MMs were the most common dermoscopic findings. Crypts, comedo-like opening, milia-like cysts, fissures, and hairpin vessels appeared more frequently in MAs (P < .05). However, atypical pigment networks, blue-white veils, pseudopods and streaks, and atypical vessels were more common in MMs (P < .05). MAs often showed melanoma-specific dermoscopic findings, especially blue-white veils (22.1%). Furthermore, fissures (42.4%), crypts (21.2%), and comedo-like openings (15.2%) were observed in MMs, although they are typically benign patterns.
Conclusion
Differences in dermoscopic patterns might provide important clues for the differential diagnosis of MA-like lesions. However, MAs such as MMs and true-benign MAs may overlap clinically in appearance and on dermoscopy. Several benign patterns were frequently observed in MMs (fissures, globular pattern, crypts, comedo-like openings, cerebriform appearance, and milia-like cysts), and several malignant patterns were observed in MAs (blue-white veil, pseudopod, and atypical pigment network). Importantly, if any of the melanoma-associated features or atypical vessels are present, the lesion should be biopsied to establish a diagnosis.
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