Moles: The Dysplastic Nevus Controversy

Take Home Massage: The term “Dysplastic Nevus” refers to a clinical lesion (an atypical mole) as well as a clinical presentation (Dysplastic Nevus Syndrome). It also refers to a histological diagnosis (somewhere between a nevus and malignant melanoma) and the term in OUR opinion should not be used…its definition is confusing and can lead to patient fear as well as physicians of other specialties who read this term in medical reports.

Comments:

-Under the microscope (histology) dysplastic nevus can refer to a nevus with moderate-to-severe atypia of melanocytes but can also fit into the definition of melanoma in situ.

-In my personal experience, when I was a medical student in my 4th year, a clinical professor showed me a melanocytic nevus and after reading it in textbooks, I thought intelligent to answer dysplastic nevus…”what are you talking about !” Granted it was asymmetrical (and fitted into the ABCD) rule but when learning more I found there is a dysplastic nevus syndrome…again this highlights the inconsistencies already present at the clinical level.

-Will confocal microscopy help…the question is completely open. (Reflectance Confocal Microscopy, RCM)

Abstract

-The concept of dysplastic nevus arises from the observation by WH Clark Jr. in 1978 of increased melanoma (MM) incidence in families with multiple nevi. Clinically, they usually present as larger, more irregular and non homogenously pigmented lesions than common nevi. Histopathologically, dysplastic nevi are characterized by a combination of architectural disorder and cytological atypia along with stromal response, giving them features which overlap both with common nevi and MM. These lesions were considered an intermediate stage between common nevi and MM. From these observations, a pathogenetic model for stepwise development of MM was proposed and the concept was extended to include sporadic dysplastic nevi as MM precursors. Over 30 years after its proposal, this model remains controversial. In fact, the clinical definition of dysplastic nevus is not clear and non reproducible, limitations in recognition of early MM versus dysplastic nevus exist, and correlation between histologic dysplasia and clinical atypia is weak. Even dermoscopy, which enables digital follow-up of skin lesions and detection of small changes useful for identifying featureless MMs, is not able to accurately identify dysplastic nevi in vivo. In vivo reflectance confocal microscopy (RCM) opens a new window in the diagnosis and definition of skin tumours. Its cellular-level resolution and horizontal sectioning show excellent correlation with histopathology and dermoscopy. As on histology, on RCM, not only do dysplastic nevi share overlapping features with melanoma, but non-dysplastic nevi can show features that overlap with those seen in dysplastic nevi and melanoma. Thus, the combination of technologies and an appropriate clinical approach is of outmost importance in managing patients with atypical moles and limit the excision of benign lesions.

Reference: Regional Congress of Dermatology (RCD) 2016 – Singapore. RCD16-0479 Challenge and controversies in the management of patients with multiple dysplastic nevi G. Pellacani1 1University of Modena and Reggio Emilia, Dermatology, Modena, Italy