Metastatic Cellular Blue Nevus: A Rare Case With Metastasis Beyond Regional Nodes

In this study, we present a rare case of a 35-year-old man with a long-standing blue-black lesion on his left hand with subsequent infraclavicular and axillary lymph node tumor deposits. The hand lesion and lymph nodes were excised revealing histological, immunohistochemical, and molecular findings consistent with cellular blue nevus. Despite nonregional lymph node involvement, there has been no progression at 12-months follow-up. This is an index case of a cellular blue nevus with metastasis to both regional and nonregional lymph nodes. The lack of atypical/malignant features in this lesion makes the metastatic behavior extraordinary, and hence the prognosis of lesions of this type is indeterminate.