This blog series highlights conditions that have a strong impact on people of color and appears as part of Project IMPACT: Improving Medicine’s Power to Address Care and Treatment.
Longitudinal melanonychia, also called “melanonychia striata,” is a longitudinal pigmented band extending from the nail matrix to the free edge of the nail. It is caused by increased activity of melanocytes or increased number of melanocytes in the nail matrix, with resulting melanin deposition in the nail plate. This may be as a result of local trauma, systemic diseases, infections, medications, nevi, or melanoma.
How does Longitudinal Melanonychia impact people of color?
Longitudinal melanonychia most commonly presents in individuals with darker skin colors, including Black, Asian, and Hispanic individuals as well as those of Middle-Eastern descent.
What to look for:
One or more brown or black bands in one or more nails, extending from the nail matrix to the free edge of the nail.
It is important to rule out acral lentiginous melanoma, which can be in the differential for longitudinal melanonychia.
Nails prone to trauma or those used for grasping (thumb, index, and middle fingers) are most frequently affected. Multiple nails are often affected, this is different from acral lentiginous melanoma, where typically only one nail is usually involved.
If there are areas of the longitudinal band lacking pigment, the pigment is broader proximally vs. distally, and/or there is pigment on the periungual skin, also known as Hutchinson sign, this is most likely an acral lentiginous melanoma.
- Greenish or blackish pigmentation from gram negative bacteria, most commonly from Pseudomonas or Proteus
- Subungual hematoma
- Exogenous nail pigmentation
- Subungual melanoma
No treatment is necessary for longitudinal melanonychia caused by melanin deposition from increased activity of melanocytes or increased number of melanocytes in the nail matrix.
The treatment of underlying causes, including the withdrawal of any offending drug, avoidance of trauma, or treatment of infections may delay the progression of pigmentation associated with longitudinal melanonychia of benign etiology.
Patients should be counseled to self-examine and to note any morphological changes in pigmentation.
Nail matrix biopsy should be performed for any evolving longitudinal band or any new band in an adult without an obvious cause.
Acral lentiginous melanoma or subungual melanoma can be managed by wide local excision or digit amputation with or without lymph node mapping / biopsy depending on depth and staging.
Leung AKC, Lam JM, Leong KF, Sergi CM. Melanonychia striata: clarifying behind the Black Curtain. A review on clinical evaluation and management of the 21st century. Int J Dermatol. 2019 Nov;58(11):1239-1245.
Singal A, Bisherwal K. Melanonychia: Etiology, Diagnosis, and Treatment. Indian Dermatol Online J. 2020 Jan 13;11(1):1-11.
Lin WM, Burgin S, Lipner S. Longitudinal melanonychia. VisualDx. Updated June 8, 2021. Accessed July 20, 2021.
This Project IMPACT blog series was created to highlight dermatologic conditions that disproportionately affect people of color. By improving diagnosis in skin of color we can reduce racial disparities in healthcare.
More in this series:
- The Impact of Nevus of Ito
- The Impact of Nevus of Ota
- The Impact of Lichen Scleroderma
- The Impact of Lichen Planopilaris
- The Impact of Traction Alopecia
- The Impact of Pomade Acne
- The Impact of Acne Keloidalis Nuchae
- The Impact of Pseudofolliculitis Barbae