Clinical spectrum of cutaneous melanoma morphology

Publication date: January 2019

Source: Journal of the American Academy of Dermatology, Volume 80, Issue 1

Author(s): Nikolai Klebanov, Nicole S. Gunasekera, William M. Lin, Elena B. Hawryluk, David M. Miller, Bobby Y. Reddy, Mitalee P. Christman, Derek Beaulieu, Suvithan Rajadurai, Lyn M. Duncan, Arthur J. Sober, Hensin Tsao

Background

Melanoma can mimic other cutaneous lesions, but the full spectrum and prevalence of these morphologic variants remain largely unknown.

Objective

To classify nonacral cutaneous melanomas into distinct morphologic clusters and characterize clusters' clinicopathologic features.

Methods

All pathologic melanoma diagnoses (occurring during 2011-2016) were reviewed for routine prebiopsy digital photographs (n = 400). Six dermatologists independently assigned lesions into 1 of 14 diagnostic classes on the basis of morphology. Image consensus clusters were generated by K-means; clinicopathologic features were compared with analysis of variance and χ².

Results

Five morphologic clusters were identified: typical (n = 136), nevus-like (n = 81), amelanotic/nonmelanoma skin cancer (NMSC)–like (n = 70), seborrheic keratosis (SK)–like (n = 68), and lentigo/lentigo maligna (LM)–like (n = 45) melanomas. Nevus-like melanomas were found in younger patients. Nevus-like and lentigo/LM-like melanomas tended to be thinner and more likely identified on routine dermatologic examinations. NMSC-like melanomas were tender, thicker, more mitotically active, and associated with prior NMSC. Typical and SK-like melanomas had similar clinicopathologic features.

Limitations

Cluster subdivision yielded diminished sample sizes. Visual assignment was performed without clinical context.

Conclusion

When primary cutaneous melanomas were assigned into diagnostic groups and subjected to novel consensus clustering, recurrent morphologic patterns emerged. The spectrum of these morphologies was unexpectedly diverse, which might have implications for visual training and possibly clinical diagnosis.

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