This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: miscellaneous, Subject name: Dental
Psoralen-A is used in the treatment of - 
Select and explain. 
A. Pemphigus, B. Vitiligo, C. Pityriasis alba, D. Icthyosis
B: Vitiligo
Answer: B: Vitiligo 
Explanation: Psoralen and many of its derivatives are naturally occurring tricyclic furocoumarins. The derivative most widely used in photochemotherapy is 8 - methoxypsoralen (8MOP, methoxsalen, xanthotoxin) which is principally of plant origin but it is available as a synthetic drug. 4, 5, 8-trimethyl psoralen (TMP, trioxsalen) is a synthetic compound which is less phototoxic after oral administration and is primarily used for the treatment of vitiligo. ijdvl journal of dermatology, psoralens.