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brown nails; longitudinal brown lines; black nails

Abnormal pigment affecting the nail plate or nail bed or both. Etiology: 1) pigmentation of the nail plate - Addison's disease - hemochromatosis - gold therapy - arsenic intoxication - azidothymidine [2] - minocycline [2] - Nelson's syndrome 2) pigmentation of the nail plate & bed - melanoma (may also pigment proximal nail fold) - suspect melanoma when proximal nail fold involved 3) 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 [3] Clinical manifestations: - longitudinal brown lines may extend from tip of nail into the lunula [3] - these are benign if < 3 mm in width Image [3] Special laboratory: - 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

Related

Hutchinson's sign; periungual pigmentation

Specific

melanonychia; longitudinal melanonychia; melanonychia striata

General

nail disease

References

  1. Color Atlas & Synopsis of Clinical Dermatology, Common & Serious Diseases, 3rd ed, Fitzpatrick et al, McGraw Hill, NY, 1997, pg 503
  2. Medical Knowledge Self Assessment Program (MKSAP) 17, American College of Physicians, Philadelphia 2015
  3. Brady MP Fingernail and Toenail Abnormalities: Nail the Diagnosis. Medscape March 17, 2021 https://reference.medscape.com/slideshow/fingernail-abnormalities-6002456