This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Psoriasis, Subject name: Skin
[{'content': 'PUVA treatment is not used in: \nSelect and explain. \nA. Melasma, B. Vitiligo, C. Psoriasis, D. Cutaneous T cell lymphoma', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans: A (Melasma) Ref: Rook's Dermatology, 8th edExplanation:PUVA TherapyPsoralens + UV-A radiationThree Psoralens are used clinically8 methoxypsoralen (8 MOP)5 methoxypsoralen ( 5 MOP)Triniethyl psoralen (TMP)They are active only when combined w ith UVA radiation.It interferes with DNA synthesis and blocks epidermal cell proliferation.Also has immunomodulatory and immunosuppressive effects.Induced epidermal thickening and melanogenesis.DosageOral 8-MOP given in a dose of 0.6 -0.8 mg/kg/ weight/day.Two hours later, patient is exposed to UV-A radiation at a dose of 1 Joule/square cmUV-A dose gradually increased depending on skin type and onset of erythemaTherapy given 2 -3 times per weekNumber of exposures required for control: 15 - 25IndicationsPsoriasisVitiligoPhotodermatosesCutaneous T-eell lymphomaSide effectsNausea and VomitingCutaneous:Acute sunburnIrreversible pigmentationPUVA LentigenesActinic keratosesPremature aging of skinOcular - Cataract (Prevented by using sunglasses during treatment)Carcinogenesis", 'role': 'assistant'}]