<unk>  is a cutaneous condition which is exclusively seen in children, usually involving one finger, most commonly the thumb or index finger, with the affected nail showing subungual hyperkeratosis and onycholysis.
Parakeratosis pustulosa
Ichthyosis bullosa of Siemens
Ichthyosis acquisita
Cutaneous lupus mucinosis
Nummular dermatitis
Sycosis vulgaris
Keratolysis exfoliativa
Malassezia folliculitis