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Author: William Hao Syuen Ng, Medical Student, University of Newcastle, Newcastle, Australia; Dr Arianejad Parisa Fatemeh, Dermatologist, The Dermatology and Skin Cancer Centre, Gosford, Australia. Copy edited by Gus Mitchell. February 2021.
Median canaliform nail dystrophy is a clinically characteristic change in the nail plate presenting as a midline longitudinal furrow or split and transverse ridges angled backwards in a fir-tree pattern.
Median canaliform nail dystrophy can affect all age groups, including children. Familial cases have been reported. It affects men and women equally.
Median canaliform nail dystrophy is an acquired nail change believed to be due to microtrauma of the nail matrix, resulting in a temporary defect in keratinocyte adhesion that affects tensile strength of the nail plate.
The majority of cases appear to be sporadic or idiopathic. There have been rare reports with systemic isotretinoin use.
A similar but distinct nail dystrophy can be caused by habitual picking of the nail fold (habit-tic deformity) and there have been very rare reports of the two conditions co-existing. Some have postulated they are variants of the same disorder.
Median canaliform nail dystrophy most commonly involves both thumbnails, although it can be unilateral. Other fingernails and toenails can also be affected.
The longitudinal split extends from the proximal nailfold to the free edge of the nail. It is usually in the midline but may be off-centre.
The transverse ridges or splits are parallel and are angled back towards the nailfold.
Macrolunulae (larger than normal lunulae) are frequently observed in the affected nails.
Median canaliform nail dystrophy
Median canaliform nail dystrophy is mainly of cosmetic concern, however the splits in the nail can catch on clothing.
Median canaliform nail dystrophy is a clinical diagnosis.
Investigations may be required if there are clinical signs to suggest an underlying tumour.
Differential diagnosis of median canaliform nail dystrophy
Median canaliform nail dystrophy may not always require active treatment.
No specific treatment has been found to be effective for median canaliform nail dystrophy. Treatments have included:
Median canaliform nail dystrophy often grows out spontaneously over months or years. Recurrence can occur.
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