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Nail biting and picking as a possible cause of longitudinal melanonychia. A study of 6 cases
1Dermatology Unit, Centre Hospitalier, Cannes, France.
Abstract:
Examination of individuals affected by onychotillomania led us to describe a new cause of longitudinal melanonychia (LM) of the finger-nails. Damage of the finger-nails was caused both manually and by chewing. The nail cuticles were usually pushed back, and biting caused pressure damage of the base of the nail. It is likely that finger-nails respond similarly to toe-nails and the matrix melanocytes can be stimulated by trauma. Such stimulation can apparently persist long after cessation of the trauma. Histological examination of the nail plates demonstrated that the pigment was melanin. In the matrix an increase in melanin content of melanocytes was found without melanocytic proliferation. LM due to onychotillomania should not be overlooked.
Insights
Onychotillomania, a nail-biting habit, can cause longitudinal melanonychia (LM) in fingernails. Trauma stimulates nail matrix melanocytes, leading to melanin deposition and nail pigmentation.
Area of Science:
- Dermatology
- Nail Diseases
Background:
- Longitudinal melanonychia (LM) is nail pigmentation often caused by melanocyte activation or proliferation.
- Onychotillomania involves compulsive manipulation and damage to the nails.
Observation:
- Individuals with onychotillomania presented with longitudinal melanonychia on their fingernails.
- Nail damage resulted from manual manipulation and biting, affecting the nail cuticles and matrix.
Findings:
- Histological examination confirmed the pigment in nail plates was melanin.
- Increased melanin content was observed in nail matrix melanocytes without evidence of melanocytic proliferation.
Implications:
- Onychotillomania is identified as a novel cause of fingernail longitudinal melanonychia.
- Trauma-induced melanocyte stimulation can lead to persistent pigmentation even after trauma cessation.