<prompt> Arthritis mutilans is a feature of?Lichen planusPsoriasisStaphylococcal scalded skin syndromeEczema  <response>: Ans. b Psoriasis. Ref. Harrison sprinciples of medicine -18thChapter 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. 