Melanonychia striataL60.8

Stripy brown/black discoloration (pigmentation) of different origin, rarely occurring in Caucasians, running longitudinally across the nail plate.

Frequently as melanocytic pigmentation in dark ethnic groups (96% of those over 50!).

Melanocytes are present in the nail root. These are inactive in Caucasians under physiological conditions. They become active by certain exogenous or endogenous factors and thus melanin-forming. This then leads to nail pigmentation of varying widths and streaks.

Melanocytic, microbiological, tumorous or endogenous factors have been described as triggers:

• Physiologic in dark ethnicities (skin types IV and V).
• Longitudinal melanonychia due to hyperplasia of melanocytes:
  • Melanocytic nevus of the nail root or nail bed
  • Malignant melanoma of the nail root or nail bed
  • Laugier-Hunziker syndrome
  • Peutz-Jeghers syndrome
  • Leopard syndrome
• Longitudinal melanonychia due to drugs:
  • Antibiotics (e.g. tetracycline)
  • Antimalarials ( Chloroquine)
  • Anticonvulsants ( phenytoin)
  • Cytostatic drugs (hydroxyurea, cyclophosphamide)
  • Virustatics.
• Longitudinal melanonychia in metabolic diseases:
  • Hyperthyroidism
  • M. Addison
  • Hemosiderosis
  • Vitamin B 12 deficiency
  • Porphyria cutanea tarda.
• Longitudinal melanonychia due to microbiological causes:
  • Onychomycoses:
    • Scopulariopsis brevicaulis
    • Trichophyton soudanense
    • Alternaria tenuissima
    • Fusarium oxysporum
    • Scytalidium dimidiatum.
  • Bacterial causes:
    • Pseudomonas aeruginosa
    • Proteus spp.

If a malignant melanoma is suspected, a bioptic examination is necessary with appropriate surgical measures. S.u. melanoma, subunguales.

In case of melanocytic nail pigmentation, an exact and reliable clinical control of the findings (with photo documentation) is necessary.

In most cases it is a harmless anomaly, which can regress even after years of existence (see figure with control photographs).

A subungual malignant melanoma that cannot be excluded - in adults a malignancy rate between 5 and 10% is assumed (Cooper 2015) - shows progressive growth, recognizable by the widening of the pigment strip of a deepening of the staining and signs of onychodystophy (due to the invasive-displacing growth of the tumor into the nail matrix).

In children, melanoma development is an absolute rarity.

However, the diagnosis of "malignancy" is only possible by biopsy (growth disturbance of the nail matrix)....

Diagnostics: Clinic, reflected light microscopy, biopsy (from nail root or nail bed). Diagnostic confirmation (type of pigment) via histological or microbiological evidence of the cause.

1. Andre J et al (2003) Longitudinal melanonychia. J Am Acad Dermatol 49: 776
2. Cooper C et al.(2015) A clinical, histopathologic, and outcome study of melanonychia striata
   inchildhood. J Am Acad Dermatol 72:773-779
3. Haneke E (1991) Laugier-Hunziker-Baran syndrome. Dermatologist 42: 512-515
4. Kreusch J et al (1992) Incident light microscopic evaluation of pigmented nail lesions. Dt Dermatol 7: 1006-1015
5. Neynaber S et al (2004) Longitudinal melanonychia associated with hydroxyarbamide ingestion. JDDG 2: 588-591
6. Parodi P et al (2003) Desmoplastic melanoma of the nail. Ann Plast Surg 50: 658-662

7. Prat C et al (2008) Longitudinal melanonychia as the first sign of Addison's disease. J Am Acad Dermatol 58:522-524.

8. Van Laborde S et al (2000) Developments in the treatment of nail psoriasis, melanonychia striata, and onychomycosis. A review of the literature. Dermatol Clin 18: 37-46