When primary cutaneous melanomas were assigned into diagnostic groups and subjected to novel consensus clustering, recurrent morphological patterns emerged, according to a recent study. Furthermore, the spectrum of these morphologies was unexpectedly diverse, which may have implications for visual training and possibly clinical diagnosis. All pathological melanoma diagnoses (2011-2016) were reviewed for routine pre-biopsy digital photographs (n=400). 6 dermatologists independently assigned lesions into 1 of 14 diagnostic classes based on morphology. Image consensus clusters were generated by K-means; clinicopathological features were compared with ANOVA and chi-square. Researchers found:

• 5 morphological clusters were identified: “typical melanoma” (n=136), “nevus-like” (n=81), “amelanotic/non-melanoma skin cancer (NMSC)-like” (n=70), “seborrheic keratosis (SK)-like” (n=68), and “lentigo/lentigo maligna (LM)-like” (n=45).
• Nevus-like melanomas were found in younger patients.
• Nevus- and lentigo/LM-like melanomas tended to be thinner and more likely identified on routine dermatological exam.
• NMSC-like melanomas were tender, thicker, more mitotically active, and associated with prior NMSC.
• Typical and SK-like melanomas had similar clinicopathological features.