The surname Nguyen is believed to have originated in the Chinese surname Ruan (in the Mandarin language) or Yuen (Cantonese), owing to Chinaâs long domination over Vietnam.
Tinea nigra is a fungal infection that is mainly seen on the palms of the hands or soles of the feet causing a dark brown to black discoloration of the affected skin. The word tinea means a fungal infection and nigra means black.
Other less common conditions that can cause dark brown to black spots include: 1  Riehl melanosis: brown pigment condition on the neck and face. 2  Poikiloderma of Civattea: dry and scaly patches on the neck and face. 3  Erythromelanosisfollicularis. 4  Lineafusca: long skin markings.