Abstract: A 19-year-old youngster presented with palmplantar keratotic papules and patches, dyspigmentation on the trunk and proximal upper extremities over a year. He had a history of psoriasis vulgaris for 8 years. In the past 2 years, he has been taking some self-made pills (unknown ingredients) by a traditional Chinese medicine practitioner at a local clinic. Hyperpigmented patches mixed with hypopigmented macules were found on the body and proximal upper extremities. Some coalesced into patches with the file-like sensation. The level of arsenic in blood and urine were both elevated. The content of arsenic in self-made pills was 1.5 mg/100 g. The patient was told to stop taking the traditional Chinese medicine pills. The patient was treated with sodium dimercaptopropanesulfonate and acitretin capsules. 0.1% tretinoin cream was enclosed on the palms and soles. After 2 months, the palmoplantar hyperkeratosis and the dyspigmentation on the trunk were both markedly improved, but some sparsely-distributed, scaly erythema appeared on the scalp, trunk and extremities appeared. The arsenic content in lood and urine were both normal. 

Key words: arsenical keratosis, psoriasis