A case of incidentally found metastatic malignant melanoma with unknown primary site in congenital systemic dermal melanocytosis patient

Abstract

A 42-year-old man presented with numerous gray-bluish hyperpigmented macules and patches on face, trunk and both extremities since birth. He was diagnosed of malignant melanoma of liver at Gastro-intestinology department and referred to our Dermatology department for skin biopsy to find the primary skin lesion of melanoma. Skin biopsy was done on 5 most suspicious lesions, but the results were all consistent with blue nevus. Through endoscopy and colonoscopy, multiple dark-bluish hyperpigmented macules were also found on stomach, ileum and rectum. The patient was referred to Hemato-oncology department and planning for chemotherapy. Dermal melanocytosis is characterized by the presence of ectopic melanocytes in the dermis. There are several morphologic forms, such as the blue nevus, the mongolian spot, the nevus of Ota, and the nevus of Ito. We define this case as the congenital systemic dermal melanocytosis. Herein, we report a extremely rare case of congenital systemic dermal melanocytosis patient with incidentally found metastatic malignant melanoma with unknown primary site.