Abstract

Primary dermal melanoma (PDM) is a rare (<1%), distinct variant of cutaneous melanoma (CM) characterized as a solitary dermal/subcutaneous melanoma tumor without epidermal involvement. Literature suggests its pathogenesis to be largely unclear and presentation to be heterogeneous, with inconsistent distinguishable immunohistochemical and genetic differences between PDM and CM. Telomerase reverse transcriptase (TERT) promoter region mutations have been well documented in the etiopathogenesis of CM, but to the authors’ knowledge has only been reported in 1 previous case of PDM to date. Henceforth, we provide a novel case series of three dermal entities diagnosed as PDM with TERT positivity via next-generation sequencing. All three patients (n=3) were adults (ages 53, 60, and 81; female-to-male ratio 2:1) with lesions involving the left cheek, right arm, and right thigh, respectively. No patients had prior histories significant for CM. Breslow depth of the lesions ranged from 0.7 to 21 millimeters with one lesion (n=1/3, 33%) demonstrating ulceration with NRAS co-expression. A separate lesion (n=1/3, 33%) also showed sentinel lymph node involvement with BRAF positivity. Epidermal involvement was not detected in histology for any case. Since the prognosis of PDM is more favorable than CM, correct identification is essential in preventing diagnostic pitfalls and patient mismanagement. Thus, this report provides new insight into TERT as a potentially similar genetic driver behind PDM and CM while offering a discussion regarding the importance of clinical correlation when diagnosing dermal melanocytic lesions and advocacy for more research regarding this controversial entity.