Dermatopathology Molecular Diagnostics

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The UMHC Dermatopathology Molecular Diagnostic Laboratory (DPML) offers state of the art molecular diagnostic testing for melanocytic neoplasms and other solid tumors. The tests are intended to aid in the more precise diagnosis of histologically ambiguous neoplasms. This category of atypical lesions cannot be definitively classified as benign or malignant using histopathological criteria alone. Such lesions are usually diagnosed using terms that imply various degrees of uncertainty in regard to their malignant potential and create the possibility for mismanagement including either over or under treatment. Molecular analysis may allow for more precise risk prognostication in these challenging lesions, avoiding unnecessarily aggressive treatment for low-risk lesions, and providing support for appropriate surgical management and staging for high-risk lesions.

Multiprobe FISH Assay and SNP Chromosomal Microarray Assay

Currently, DPML offers 2 tests to aid in the diagnosis of histologically ambiguous melanocytic tumors, a multiprobe FISH assay, and a SNP Chromosomal Microarray assay. Both tests are optimized for formalin-fixed, paraffin-embedded tissue from small biopsies. For both tests, a positive result favors a diagnosis of melanoma while a negative result one of nevus.

The multiprobe FISH assay is designed to detect copy number abnormalities at probed loci via fluorescence in situ hybridization (FISH) in FFPE tissue specimens.  Three multiprobe FISH panels are available. Panel 1 include probes 6p25 (RREB1), 6q23 (MYB), 11q13 (CCND1) and CEP6; panel 2 include 9q21 (CDKN2A) and CEP9; panel 3 include 8q24 (MYC). Panel 1 is recommended for all histologically ambiguous melanocytic tumors. The addition of panels 2 and 3 increases assay sensitivity for selected melanocytic neoplasms including spitzoid tumors and nevoid melanomas.

SNP microarray analysis is performed using the ThermoFisher OncoScan (TM) FFPE Assay Kit. The assay utilizes a Molecular Inversion Probe (MIP) technology, which is optimized for highly degraded FFPE samples (probe interrogation site of just 40 base pairs). For copy number analysis the assay has a resolution of 50-100 kb in genomic regions spanning selected 900 cancer genes and of 300 kb outside of these regions.

Besides melanocytic tumors, our lab also offers another 2 tests to aid in the diagnosis and prognosis of other types of tumors FISH for malignancy and SNP Chromosomal Microarray Analysis-Tumor.

FISH for malignancy is designated as single probe FISH for CDKN2A, MYC, or BAP1. The purpose of these tests is to aid in the diagnosis and prognosis of selected neoplasms including atypical vascular lesions (MYC), BAP1-inactivated tumors such as melanocytic tumors or mesothelioma (BAP1) and tumors characterized by homozygous CDKN2A deletion such as mesothelioma.

SNP Chromosomal Microarray Analysis-Tumor is designated to aid in the diagnosis of copy number variations (CNVs) associated tumors. Both tests are optimized for formalin-fixed, paraffin-embedded tissue from small biopsies.

Specimens submitted to the Dermatopathology Molecular Diagnostic Laboratory must be properly labeled and accompanied by a completed DPML Test Requisition. Please refer to the MLabs Test Catalog for available assays and specimen collection requirements.