Table 1.

Morphological classification of melanonychia

Pattern of nail pigmentation	Clinical feature	Causes
Longitudinal melanonychia or melanonychia striata [Figure 1]	Longitudinal brown-black/grey band extending proximally from nail matrix or cuticle to distal free edge of the nail plate	Lentigine, nevus, melanoma
Diffuse or Total melanonychia [Figure 2]	Involvement of the entire nail plate by melanin	Constitutional/racial, drugs, infections
Transverse melanonychia [Figure 3]	Transverse band running across the width of nail plate	Drugs