Concordance of reflectance confocal microscopy and gene expression profiling for melanocytic lesions with uncertain malignant potential: A case series

A clinical impact study of dermatologists' use of diagnostic gene expression profile testing to guide patient management

Aim: Cutaneous melanocytic neoplasms with diagnostic and/or clinical ambiguity pose patient management challenges. Methods: Six randomized case scenarios with diagnostic/clinical uncertainty were described with/without a benign or malignant diagnostic gene expression profile (GEP) result. Results: Clinical impact was assessed by reporting the mean increase/decrease of management changes normalized to baseline (n = 32 dermatologists). Benign GEP results prompted clinicians to decrease surgical margins (84.2%). Malignant GEP results escalated surgical excision recommendations (100%). A majority (72.2%) reduced and nearly all (98.9%) increased follow-up frequency for benign or malignant GEP results, respectively. There was an overall increase in management plan confidence with GEP results. Conclusion: Diagnostic GEP tests help guide clinical decision-making in a variety of diagnostically ambiguous or clinicopathologically discordant scenarios.

Diagnostic utility of the 23-gene expression profile test for an atypical intradermal melanocytic proliferation

Ancillary tests such as immunohistochemistry (IHC) and gene expression profile (GEP) testing may be needed to arrive at a definitive diagnosis for some atypical melanocytic neoplasms. A 34-year-old male with a family history of melanoma presented with a large, heterogeneous melanocytic lesion on the cheek. Histopathological review of two biopsies revealed an atypical intradermal melanocytic proliferation with spitzoid features without ulceration or regression. Scattered mitotic figures were identified. In addition to performing SOX10 IHC, PRAME and HMB45 staining highlighted weak, patchy positivity that was stronger in superficial, pleomorphic melanocytes (Ki-67, 5-7% mitotic rate). Based on these concerning but ambiguous IHC results and lingering concern for melanoma reiterated by other consulting dermatopathologists, the 23-GEP was requested for both specimens, which both returned a malignant result. The inconclusive histopathological features of malignancy were resolved by 23-GEP testing, facilitating a final diagnosis of malignant melanoma (pT3a, 2.5 mm Breslow depth, Clark's level IV).