Melanonychia 

  • Author: Anokhi Jambusaria-Pahlajani, MD; Chief Editor: Dirk M Elston, MD   more...
 
Updated: Mar 19, 2010
 

Background

Melanonychia is brown or black pigmentation of the nail unit. Melanonychia commonly presents as pigmented band arranged lengthwise along the nail unit, and this presentation is known as longitudinal (LM) melanonychia or melanonychia striata. The most important cause of melanonychia is subungual melanoma, (as shown in the image below), although a variety of other causes includes physiologic longitudinal melanonychia, systemic disorders, trauma, inflammatory disorders, fungal infections, drugs, and benign melanocytic hyperplasias.

Pigmented longitudinal streak secondary to a nail Pigmented longitudinal streak secondary to a nail matrix melanoma.
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Pathophysiology

Melanonychia most often occurs because of increased production of melanin by melanocytes in the nail matrix. A healthy adult has approximately 200 melanocytes per mm2 in the nail matrix, of which the majority remain dormant. When these melanocytes are activated, melanosomes filled with melanin are transferred to differentiating matrix cells, which migrate distally as they become nail plate onychocytes.[1] This results in a visible band of pigmentation in the nail plate.

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Epidemiology

Frequency

International

Physiologic or racial melanonychia is more common in darkly pigmented individuals, such as African Americans or Hispanics. Seventy-seven percent of African American individuals older than 20 years and almost 100% older than 50 years have evidence of this condition.[2, 3] Longitudinal melanonychia is present in 10-20% of Japanese individuals.[4] In the general white population, the prevalence of longitudinal melanonychia is 1.4%.[5]

In a study of 48 Hispanic patients with longitudinal melanonychia, 4 (5.7%) cases were associated with benign melanocytic hyperplasia and 4 (5.7%) cases had a nail apparatus malignancy.[6]

The prevalence of affected individuals increases with age.[5, 7]

Mortality/Morbidity

The morbidity and mortality of melanonychia is dependent on the underlying cause.

Melanonychia secondary to subungual melanoma has the highest morbidity and mortality compared with other body sites, with reported 5- and 10-year survival rates of 30% and 13%, respectively.[8]

Race

The frequency of melanonychia varies by the degree of skin pigmentation, as described in Frequency, International.

Sex

Melanonychia affects males and females equally.[7]

Age

Typically, melanonychia is more common in older individuals. In children, melanonychia is often caused by melanocytic nevi. Subungual melanoma or melanoma in situ is very rare in children,[9, 10] but has been reported.[11]

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Contributor Information and Disclosures
Author

Anokhi Jambusaria-Pahlajani, MD  Resident Physician, Department of Dermatology, University of Pennsylvania School of Medicine

Anokhi Jambusaria-Pahlajani, MD is a member of the following medical societies: American Association of Physicians of Indian Origin and Phi Beta Kappa

Disclosure: Nothing to disclose.

Coauthor(s)

Adam I Rubin, MD  Assistant Professor of Dermatology, University of Pennsylvania School of Medicine

Adam I Rubin, MD is a member of the following medical societies: American Academy of Dermatology, American Medical Association, American Society of Dermatopathology, International Society of Dermatology, International Society of Dermatopathology, Medical Dermatology Society, and Women's Dermatologic Society

Disclosure: Nothing to disclose.

Specialty Editor Board

Richard K Scher, MD  Professor of Dermatology, University of North Carolina

Richard K Scher, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American College of Cryosurgery, American College of Physicians, American Dermatological Association, American Geriatrics Society, American Medical Association, Association of Military Surgeons of the US, International Society for Dermatologic Surgery, New York Academy of Sciences, Noah Worcester Dermatological Society, Rhode Island Medical Society, and Society for Investigative Dermatology

Disclosure: Nothing to disclose.

David F Butler, MD  Professor of Dermatology, Texas A&M University College of Medicine; Chair, Department of Dermatology, Director, Dermatology Residency Training Program, Scott and White Clinic, Northside Clinic

David F Butler, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Medical Association, American Society for Dermatologic Surgery, American Society for MOHS Surgery, Association of Military Dermatologists, and Phi Beta Kappa

Disclosure: Nothing to disclose.

Jeffrey Meffert, MD  Assistant Clinical Professor of Dermatology, University of Texas Health Science Center-San Antonio

Jeffrey Meffert, MD is a member of the following medical societies: American Academy of Dermatology, American Medical Association, Association of Military Dermatologists, and Texas Dermatological Society

Disclosure: Nothing to disclose.

Catherine M Quirk, MD  Clinical Assistant Professor, Department of Dermatology, University of Pennsylvania

Catherine M Quirk, MD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Dermatology

Disclosure: Nothing to disclose.

Chief Editor

Dirk M Elston, MD  Director, Department of Dermatology, Geisinger Medical Center

Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology

Disclosure: Nothing to disclose.

References

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Longitudinal melanonychia secondary to a nevus.
Pigmented longitudinal streak secondary to a nail matrix melanoma.
 
 
 
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