Abstract

Melanoma with marked syringotropism, or syringotropic melanoma (SM), is a rare variant of melanoma with prominent involvement of eccrine apparatus. SM are commonly reported in acral, head, and neck regions, and pose diagnostic and staging challenges in assessing accurate depth of invasion. Syringotropic areas usually demonstrate a deeper dermal invasion than conventional invasive foci of melanoma. Our patient is a 74 year-old-man with a prior history of stage IV melanoma treated with ipilimumab, who recently developed two synchronous primary melanomas involving right shoulder and left neck respectively. The shoulder lesion showed a superficial spreading melanoma with 0.9 mm depth of invasion. The neck lesion was a larger superficial spreading melanoma with 2.6 mm depth of conventional invasion and continuous extensive eccrine unit involvement. Syringotropic spread measured up to 5.0 mm from the surface epidermis. Targeted NGS testing, 161 gene panel, of SM revealed high tumor gene mutation burden with pathogenic mutations involving NF1, ATRX, BRCA1, CTNNB1, KDR, POLE, RAC1, RNF43, TP53, and TSC2 genes. Loss of function NF1 mutation and with RAC1 mutation are known to occur in melanoma arising from chronically sun-damaged skin. However, additional mutations, particularly ATRX, are common in mucosal melanomas, and RNF43/CTNNB1 variants activating Wnt signaling pathway may be related to their syringotropic nature. To our knowledge, our case represents the first report of genetic characteristics in a SM. Further studies are needed to identify if any of these driver mutations are recurrent and may lead to the phenotype of SM.

Financial Disclosure: No current or relevant financial relationships exist.