Historical, clinical, and dermoscopic characteristics of thin nodular melanoma

Nodular melanoma (NM), representing 15% to 30% of all melanomas, constitutes nearly half of all melanomas thicker than 2 mm. Nodular melanoma frequently lacks clinical features seen in other melanoma subtypes and has a faster growth rate. We reviewed a series of cases of NM that was less than 1.3 mm thick to identify historical, clinical, and dermoscopic factors that may facilitate earlier diagnosis of NM, with the hope of reducing its associated morbidity and mortality.

The thin NM lesions we analyzed had a rather subtle clinical appearance, often lacking the ABCD (asymmetry, border irregularity, color variegation, and diameter greater than 6 mm) criteria. On dermoscopy, most lesions had a homogeneous disorganized asymmetric pattern or a featureless pattern with atypical vessels. Although many dermoscopic features seen in other melanoma subtypes were frequently absent, some features such as a blue-white veil, structureless areas, and atypical vascular structures were often identified.

The often unremarkable clinical presentation of NM necessitates physicians and patients to be wary of new or changing lesions. Dermoscopy may help increase suspicion in early NM because dermoscopic features are typically more suggestive of malignancy than clinical ones. We hope that secondary prevention efforts combined with prompt dermatologic consultations will allow for the timely diagnosis and management of NM.