21st Century Dermatopathology: Molecular Diagnostics for Melanocytic Neoplasms

21st Century Dermatopathology: Molecular Diagnostics for Melanocytic Neoplasms

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Melanocytic tumors of uncertain malignant potential (MelTUMPs) and other borderline melanocytic neoplasms have long posed a significant challenge to pathologists and clinicians, and expose patients to under- or over-treatment and surveillance, thus leading to significant anxiety. The World Health Organization 4th Edition (2018) reclassified melanocytic tumors into nine “pathways” on the basis of not just histomorphology but initiating and driver mutations, and introduced benign (i.e., nevus), intermediate (i.e., melanocytoma), and malignant classifications for each of the traditional phylogenies of melanocytic tumors. Next-generation sequencing (NGS) has allowed for identification of initiating driver mutations, as well as secondary genomic alterations known to be important to melanomagenesis, and has allowed for improved classification and prognostication of the biologic behavior of borderline melanocytic neoplasms. We will discuss several such cases from the University of Washington Dermatopathology service with the aim of highlighting the importance of uniting histopathologic and molecular data in modern dermatopathology.

After viewing this lecture, participants should be able to:
1. Recognize important initiating and progressive genomic events in benign and malignant melanocytes
2. Understand “melanocytomas” (formerly known as MELTUMP or STUMP) as intermediate grade melanocytic neoplasms
3. Identify situations in which the use of next-generation sequencing and other molecular diagnostic techniques can help classify melanocytic tumors

Ata Moshiri, MD, MPH
Assistant Professor
Department of Medicine, Division of Dermatology
Department of Laboratory Medicine and Pathology
University of Washington

03/02/22