What is it melanonychia?
Benign longitudinal melanonychia
Who is at risk for melanonychia?
Melanonychia can occur in people of all ages, including children, and affects both sexes equally. It's more predominant in people with skin of color, especially Fitzpatrick type V and VI skin.
- Almost all Afro-Caribbean people will develop black-brown pigmentation of the nail at the age of 50.
- Melanonychia affects up to 20% of the Japanese.
- Fair-skinned people are the least affected.
Melanonychia can also be associated with genetic disorders, injuries, medications, nutritional deficiency, endocrine disease, connective tissue disease, inflammatory skin disease, a local tumoror nail infection.
What Causes Melanonychia?
The nail plate is hard, translucent structure made of curb. It is not normally pigmented. Melanocytes normally remain latent in the proximal matrix of the nail where the nail originates. Melanin it is deposited on the growing nail when melanocytes are activated, resulting in a pigmented band, this is longitudinal melanonychia.
the statement of melanin in the nail plate can result from 2 processes:
- Hyperplasia Melanocytic
- Melanocytic activation.
Melanocytic hyperplasia
Melanocytic hyperplasia refers to an increased number of melanocytes within the nail matrix. This may represent a benign or evil one process.
Benign hyperplasia
Melanocytic naevi they arise more commonly in children. Histologically there are nests of nevus cells.
Lentigos they are seen more often in adults. The nests are absent.
Malignant hyperplasia
Melanoma of the nail unit most commonly affects the thumbs, index fingers, and big toes.
Melanocytic activation
Melanocytic activation is an increase in the production and deposit of melanin in the nail cells (onychocytes), without an increase in the number of melanocytes. The causes of melanocytic activation are listed in the table below.
Melanonychia associated with melanocytic activation
| Physiological (functional) | Racial variation The pregnancy |
| Trauma | Nail biting, chewing, breaking and picking Friction due to foot or shoe deformity. |
| Inflammatory skin disease | Psoriasis Hallopeau acrodermatitis Lichen planus Amyloidosis |
| Non-melanocytic lesions. | Intraepidermal carcinoma Basal cell carcinoma Viral wart |
| Nutritional deficiency | Vitamin B12 or folate deficiency |
| Endocrine disorders | Addison's disease Cushing syndrome Hyperthyroidism Acromegaly |
| Other systemic disease | Hemosiderosis Cutaneous porphyria delays Human immunodeficiency virus infection (HIV) Systemic lupus erythematosus Systemic sclerosis |
| Syndromes | Laugier-Hunziker syndrome Peutz-Jeghers syndrome Touraine syndrome |
| Iatrogenic | Phototherapy X-ray exposure; electron beam therapy |
| Medicines | Chemotherapy agents (especially hydroxyurea, busulfan, bleomycin, adriamycin, doxorubicin, cyclophosphamide, 5-fluorouracil) Antimalarial therapy |
Pathogens can cause irregular melanonychia as they stimulate inflammation activating melanocytes. For example:
- Gram-negative bacteria (Proteus mirabilis, KlebsiellaPseudomonas)
- Onychomycosis due to a dermatophyte (Trichophyton rubrum) or yeast (Candida albicans)
External agents can stain the nails.
- Hair Colorant
- Henna
- Enamel
- Paint.
Discolored nails
Pigmented onychomycosis
Pseudomonas nail infection
Nail stained with dithranol
What are the possible complications of melanonychia?
Complications depend on the cause of the melanonychia.
- Subungual Melanoma: Can result in metastasis and finally, the death of the patient. Melanoma of the nail matrix is, as a rule, worse than melanoma at other sites.
- Trauma, infection, and inflammatory disease can lead to fissure and splitting of nails and unsightly or painful nails dystrophy.
What is the management of melanonychia?
When melanonychia is attributed to a benign cause, no additional treatment is necessary. Management of melanoma of the nail unit requires complete excision tumor and may require amputation of digit.
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