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Nodular melanomas identified by dermoscopic evaluation
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The majority of hypomelanotic and pigmented nodular melanoma lesions displayed dermascopic features that allowed for their diagnoses, according to recent study data.
In a five-continent study among primarily hospital-based clinics, researchers retrospectively assessed and documented the dermoscopy features of 467 lesions obtained from photographic libraries. They included 83 nodular melanoma (NM), 134 invasive non-NM, 115 nodular benign melanocytic tumors and 135 nodular nonmelanocytic tumors. All lesions were scored for dermoscopy features using modified and previously defined methodologies and categorized as amelanotic/hypomelanotic or pigmented.
NM lesions were more often amelanotic/hypomelanotic than invasive non-NM (37.3% vs. 7.5%), and pigmented NM displayed greater symmetrical pigmentation patterns compared with invasive non-NM (5.8% vs. 0.8%) with an OR of 7.6 (95% CI, 0.8-75.6). Among other positive characteristics, they also had more frequent large-diameter vessels (OR=7.6); homogenous blue pigmentation within the lesions (OR=5.6), symmetry (OR=3.8), blue-white veil (OR=3.3) and predominant peripheral vessels (OR=3.8).
Among negative features, pigmented NM less frequently than non-NM (3.8% vs. 32.5%) had atypical networks that were broadened and irregular (OR=0.08; 95% CI, 0.02-0.36). NM also less frequently displayed pigment network or pseudonetwork (OR=0.09), multiple blue-gray dots (OR=0.23) and scarlike depigmentation (OR=0.25).
When researchers used a method to classify lesions as melanocytic, nodular pigmented and non-nodular pigmented melanoma showed a sensitivity of more than 98%, but a reduced sensitivity for amelanotic/hypomelanotic NM (84%) and non-NM (50%). A model for diagnosing amelanotic/hypomelanotic malignant lesions, including basal cell carcinoma, provided a 93% sensitivity and 70% specificity for NM.
“When a progressively growing, symmetrically patterned melanocytic nodule is identified, the diagnosis of NM needs to be excluded,” the researchers wrote. “Indeed, we believe any nodular lesion that cannot be confidently diagnosed as benign should be excised.”
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