Habit-tic deformity is a form of nail dystrophy caused by habitual external trauma to the nail matrix. It is caused by nail picking of proximal nail fold.
It occurs primarily in children, although cases have been reported in adults. Habit tic deformity occurs when individuals, either consciously or unconsciously, engage in the habit of picking, pushing back, or rubbing the proximal nail fold. The thumb is the most commonly affected digit in this behavior, which can be classified as a form of obsessive-compulsive disorder.
Clinically, a dystrophy of the median aspect of the nail, primarily consisting of somewhat parallel transverse ridges extending from the proximal nail fold to the distal aspect of the nail plate, an absence of cuticle and hyperkeratotic nail fold are detected. Patients complain of nail changes, frequent infections (bacterial or fungal), sometimes anxiety and mental health problems.
Diagnosis is based on clinical presentation, history and dermoscopy. Patients may be reluctant to disclose their self-manipulation or self-inflicted nail trauma, and in some cases, they may not even be aware of their nail picking habit if it's unconscious. Often a family member will be the one to admit that they have observed the habit.
Dermoscopy may show:- Multiple obliquely oriented haemorrhages of the nail bed
- Uneven, longitudinal wavy lives that may appear to be on different planes and with varying pigmentation (eg, white, reddish-purple, brown, or black in colour) due to uneven nail growth following recurrent trauma
- Crusting and scaling.
- Median canaliform dystrophy
- Onychomycosis
- Lichen planus
- Psoriasis
- Cyanoacrylate adhesive (a type of instant glue) applied to the proximal nail fold to provide a durable barrier to trauma and to artificially recreate the absent cuticle 1-2 times per week for 6 months
- Psychotherapy
- Replacement behaviors such as squeezing stress balls
- Pharmacological treatment: antipsychotics, antidepressants, etc.