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Introduction: CGH is a biochemical genetic assay developed at the University of California, San Francisco that analyzes structural variations in genomes, known as copy number variations (CNVs). By comparing quantities of CNVs within samples to those of known tissue standards, it is possible to gauge genomic instability and in terms of melanomas, differentiate between malignant lesions versus benign atypical nevi. While CGH has gained traction in other fields,it has not been discussed in the plastic surgery literature. We present two cases from the author’s plastic surgery practice that demonstrate the impact of CGH in the management of melanoma.
Methods: A retrospective chart review of two patients from the senior author’s plastic surgery practice was conducted as part of a larger series of approximately 10 patients from the Inova Melanoma Center to identify impact of CGH testing. The patient treatment courses and outcomes were recorded in the electronic medical record.
Case Descriptions: The two patients featured presented with melanocytic skin lesions - patient 1 on the base of the left small finger and patient 2 on the base of the left fifth toe. Both patients had multiple readings of their pathology with diagnoses of melanoma made on some of the readings. Due to the ambiguity of initial biopsy results, both underwent CGH testing to determine the likelihood of a malignant melanoma. Both patients’ CGH results demonstrated atypical melanocytic lesions allowing for excisions with minimal 0.5 cm margins. Both had excellent clinical and cosmetic results.
Discussion: Comparative genomic hybridization is a technique growing in management of melanoma as a means to differentiate suspicious melanocytic lesions from malignancy versus non-melanoma atypia. With over 70,000 new melanoma diagnoses made yearly, not all concerning lesions are true melanomas, specifically spitz nevi and/or atypical nevi. These lesions possess a level of atypia, but are often indistinguishable macro/microscopically from melanomas and have traditionally posed a challenge for physicians.The ability of CGH to differentiate between them is crucial in cases such as the two presented where excision and reconstruction outcomes can vary widely depending on an accurate diagnosis. For both patients, CGH testing afforded a downgraded diagnosis and 0.5cm margins versus a larger margin and/or amputation. The polarity of such outcomes highlights the impact of CGH and its potential to augment current practices in plastic surgery and reconstruction.
Conclusion: These examples demonstrate that CGH may bolster current plastic surgery practices through accurate identification of ambiguous melanocytic lesions and tailoring resections/reconstruction in delicate areas where larger excisions could otherwise lead to amputations.CGH testing may allow plastic surgeons greater clarity when planning for resection (margins) and reconstruction of lesions in delicate regions.