Psoralen induced photo onycholysis

P VS Prasad

 Dept. of Dermatology, Rajah Muthiah Medical College. and Hospital, Annamalai University, Annamalai Nagar-608 002, India

Correspondence Address:
P VS Prasad
Dept. of Dermatology, Rajah Muthiah Medical College. and Hospital, Annamalai University, Annamalai Nagar-608 002
India

To the Editor,

Administration of oral psoralen is useful in various dermatological conditions. The adverse effects range from erythema and frank sunburn to abnormalities of immune function.[1] Pigmentation of nails and photo onycholysis have been reported earlier.[2],[3] Similar nail changes which occurred in one of the patients is detailed.

A 25-year-old male lawyer was diagnosed to have extensive vitiligo vulgaris on the extremities and was given oral ammoidine (melanocyl) 10 mg on alternate days followed by sun exposure. By the end of six months there was 90% clearance of the lesions. However at that time he developed pain in some of the finger nails. On examination all finger nails were affected sparing left thumb and middle finger. The changes included brownish pigmentation, swelling of the lateral and posterior nail folds in all the affected nails. Onycholysis occurred in 3 finger nails and in a few toe nails. KOH examination and culture test from the affected nails were negative for fungus. Routine screening tests were normal. Patient was advised to stop oral ammoidine for 3 months. The nail changes were reuturning to normal. As the vitiligenous patches were reactivating after treatment, he was restarted on the same drug with which the nail changes recurred.

Onycholysis has many possible causes. These fall into several general categories. They are (i) cutaneous diseases (psoriasis) (ii) congenital (pachyonychia congenital (iii) systemic disease (hypothyroidism) (iv) local factors (trauma and nail infection) and (iv) idiopathic."Among the drugs tetracycline induces photo onycholysis. This can occur after 5-12 months.[5] Apart from tetracyclines, PUVA therapy also induces photo onycholysis rarely.[3],[4] Our patient was on Puvasol therapy and developed the nail changes after 6 months. The remission of the nail changes after withdrawal of the drug and the recurrence after reintroduction of the drug points only towards photo onycholysis to psoralens. As the nail plate is a poor sun screen and may even concentrate solar radiation this may lead to onycholysis in photosensitivity reactions.[5] We share this report with our readers for its interest.

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