This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autoimmune Skin Disorders, Subject name: Skin
[{'content': 'Arthritis mutilans is a feature of? \nSelect and explain. \nA. Lichen planus, B. Psoriasis, C. Staphylococcal scalded skin syndrome, D. Eczema', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. b (Psoriasis). (Ref. Harrison' sprinciples of medicine -18th/Chapter 52.)PSORIASIS# Classical features:- White scaly plaques with specific distribution over the body.- Pitting (thimble) of nails.- Onychodystrophy, Subungual hypertrophy.- Arthritis mutilans, rare and late feature {pencil in cup sign, pestle in mortar sign). (MH 2008)# Treatment:- Unstable psoriasis = liberal application of topical bland emollient & supportive therapy.- PUVA therapy is used in severe cases.- Oral methotrexate, retinoids, cylosporin can be used, however systemic steroids are usually avoided for the fear of precipitating pustular psoriasis upon withdrawal.", 'role': 'assistant'}]