Question: Can you identify this condition?

A 31-year-old, otherwise healthy man presents with longitudinal splitting and ridging of the nail plate of both thumbs that had begun several months before. The affected nails appear cracked with a deep medial depression accompanied by dark, lateral projections. The patient’s medical history is unremarkable and he is not taking any medications.

The most likely diagnosis is

1. Nail psoriasis

2. Median canaliform nail dystrophy

3. Onychomycosis (tinea unguium)

4. Lichen planus

5. Onycholysis

Answer on page 513

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