INTRODUCTION
The accurate assessment of pigmented skin lesions, especially in pediatric settings, is challenging even for pigmented lesion experts.1 The current gold standard of visual assessment paired with histopathology combines two diagnostic modalities that both rely on image and pattern recognition. Inherently, image and pattern recognition are subjective leading to inter and intra-observer discrepancies that may impact how pigmented skin lesions are managed and how plans for treatment and follow-up are devised. Improved diagnostic aides and options are desirable.2-4 Furthermore, it is increasingly recognized that the way a pigmented lesion looks either clinically or under the microscope, is heavily influenced by changes in gene expression patterns that themselves are caused by mutations (in case of pigmented lesions most often acquired in a series of events as a consequence of UV damage).5 Even intricate assessments of morphological features by dermoscopy or confocal microscopy, while without doubt beneficial in the hands of trained experts, are indirect and preceded by changes that may provide superior assessment if easy ways can be found to determine their nature.6 Our team recently validated a molecular dermatology gene expression platform using adhesive patches to non-invasively collect skin samples. LINC (long intergeneic non-coding RNA 518) and/or PRAME (preferentially expressed antigen in melanoma) gene expression in adult patients differentiates primary melanomas from atypical nevi and other pigmented lesions with a NPV of over 99%, a sensitivity of 91% and a specificity of 69% to support clinicians with the management of difficult to assess pigmented lesions.2 Board certified dermatologists and pigmented lesion experts who use LINC/PRAME gene expression to help guide the management of pigmented lesions, surgically biopsy about half as often while missing fewer melanomas.3 The study presented here addresses frequent questions from clinicians who use the test described above and who wanted to know, how Spitz nevi in children and young adults, a group of pigmented skin lesions frequently very similar in morphological appearance to primary cutaneous melanomas and therefore notoriously difficult to assess,1 compare to melanomas and pediatric common nevi at the gene expression level.
MATERIALS AND METHODS
Study Subjects and Tissue Block SamplesThe 23 subjects in this archival study were male (n=9) and female (n=14) patients (median age 12) with histopathologically confirmed pigmented lesions (pediatric melanomas and
