Photo credit: Dermnetnz

In dermatology, median canaliform nail dystrophy refers to an abnormal change in the nail plate characterized by midline longitudinal furrow or split transverse ridges in fir-tree pattern that are angled backwards.

Median canaliform nail dystrophy can affect anyone at any age, even children. Men and women are affected equally. Familial cases of median canaliform nail dystrophy have also been reported.

Microtrauma of the nail matrix is responsible for causing median canaliform nail dystrophy. It results in a temporary defect in keratinocyte adhesion, which affects nail plate’s tensile strength.

Usually, cases are classified either as sporadic or idiopathic.

Habitual picking of the nail fold can cause similar but distinct nail dystrophy. In rare cases, these conditions co-exist.

Generally, median canaliform nail dystrophy involves both thumbnails, but the condition can also be unilateral. Other fingernails and toes can be affected as well.

The longitudinal split goes all the way up from the proximal nailfold to the free edge of the nail. It is usually found within the midline, but may occur off-centre.

The transverse ridges or splits are parallel and angled back towards the nailfold.

Median canaliform nail dystrophy are diagnosed based on their clinical features. However, further investigations may be done in order to avoid missing an underlying tumour.

An active treatment may not always be required. There are some general measures that are recommended to follow. For example, a bandage may be applied on an affected nail in order to prevent causing further trauma to it. If a patient is taking an implicated medication (e.g. isotretinoin), it is advised to stop taking it.

To the present day, no specific treatment has been found to be effective for a median canaliform nail dystrophy. Suggested treatments include prescribing topical steroids, topical tacrolimus, and/or phototherapy sessions.

Median canaliform nail dystrophy usually arises spontaneously over months or years. It can reoccur a few times over one’s lifetime.