#dermpathJC March 2018:
Thursday, March 22nd, 9pm EST
Article discussed: Nuclear and cytoplasmic features in the diagnosis of Clark’s nevi
Authors: Valdebran M, Bandino J, Elbendary A, Gad A, Arudra KC, Feraudy S, Elston DM.
Journal of Cutaneous Pathology, 2018;45(3):204-207.
Temporary open access available at: https://onlinelibrary.wiley.com/doi/abs/10.1111/cup.13085
Summary author: Silvija P. Gottesman, MD (@SGottesmanMD)
Journal Club Summary:
Study by Elston et al, looked at 100 Clark’s nevi and 84 melanomas for the presence of 14 various cytologic features. Cases from special sites, dysplastic nevi with severe atypia, and cases with inadequate material were excluded. In a way, controversy was avoided by looking at dysplastic nevi with mild and moderate atypia versus melanoma. For many pathologists, distinguishing typical non-severe Clark’s nevi from melanoma is not too difficult. Would have appreciated a discussion on really hard cases and how those compare to melanoma. But in those cases, it is probably best to proceed with molecular testing for a definitive answer.
14 different cytologic features were evaluated, definitions summarized in the table below.
Clark’s nevi lack mitotic figures, abnormal mitotic figures, they lack multiple nucleoli and for the most part have either absent or inconspicuous nucleolus. High nuclear to cytoplasmic ratio did not distinguish between Clark’s nevi and melanomas. Dusty cytoplasm and solid hyperchromasia is also equally seen in Clark’s nevi and melanomas.
When present in >20% of the melanocytes: pleomorphism with enlarged nucleus, notching and mitotic figures, peppered moth chromatin, multiple nucleoli prove helpful features in diagnosing melanomas.
Many pathologists make the diagnosis of Clark’s nevi based on architecture and they use the nuclear atypia for grading of the lesion.
If too many categories are used, it makes it difficult to decide on a more standardized management. Some pathologists like two tier grading (mild and severe atypia, yet 42% of pathologists (number from a poll during this journal club) use hybrid categories for grading, such as mild to moderate and moderate to severe. There are some Clark’s nevi that have no atypia and several pathologists agree.
An algorithm for treatment of dysplastic nevi based on cytologic atypia:
Mild atypia = observe
Mild to moderate = observe
Moderate, and “margins appear free” = observe
Moderate, and present at lateral margins = excise
Moderate to severe = excise
Severe = excise
It was asked during the discussion if nevi get a grade of atypia for the epidermal component and for the dermal component. A true pearl from the discussion from Dr Joseph Susa (@CutisViaLux) shared word for word “It’s one nevus. It gets one grade. It will be treated one way by the clinician. #DermpathJC” Thank you Dr Susa!
For closing thoughts, I will leave you with the “dysplastic” nevus article, a topic so neatly summarized by Dr @ClayCockerell. He too proposes a two tier grading system. https://www.ncbi.nlm.nih.gov/pubmed/26282799 Full article at http://dermpath.com/blog/counterpoint-dysplastic-nevus/
Join us next month to learn about nail pathology and how to distinguish normal versus abnormal number of melanocytes.
Silvija Gottesman, MD