brown nails; longitudinal brown lines; black nails

Introduction

Abnormal pigment affecting the nail plate or nail bed or both.

Etiology

• pigmentation of the nail plate
  • Addison's disease
  • hemochromatosis
  • gold therapy
  • arsenic intoxication
  • azidothymidine
  • minocycline
  • Nelson's syndrome
• pigmentation of the nail plate & bed
  • melanoma (may also pigment proximal nail fold)
  • suspect melanoma when proximal nail fold involved
• pigmentation of the nail bed
  • melanocytic nevus of nail matrix
  • solar lentigo
  • subungual hematoma
  • brown linear bands are a common finding in black or brown-skinned individuals (melanonychia)

Pathology

• increased melanin production by nail matrix melanocytes

Clinical manifestations

• longitudinal brown lines may extend from tip of nail into the lunula
  • these are benign if < 3 mm in width

Image

Diagnostic procedures

• nail biopsy if suspicious for melanoma
  • > 3 mm in width
  • irregular or blurred borders to the band
  • brown black discoloration of the proximal nail fold (skin proximal to nail)

Management

• reassurance & observation in the absence of suspicion of melanoma

More general terms

• nail disease

More specific terms

• melanonychia; longitudinal melanonychia; melanonychia striata

Additional terms

• Hutchinson's sign; periungual pigmentation