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Melanonychia

What is it melanonychia?

Melanonychia is the brown or black discoloration of a nail. Can be diffuse or take the form of a longitudinal band.

Benign longitudinal melanonychia

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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

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Pigmented onychomycosis

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Pseudomonas nail infection

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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.