This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Skin
[{'content': "Which of the following conditions produce a positive Darier's sign? \nSelect and explain. \nA. Darier's disease, B. Uicaria pigmentosa, C. Hailey Hailey disease, D. Telangiectasia macularis eruptiva perstans", 'role': 'user'}, {'content': "Answer: B \nExplanation: Uicaria pigmentosa is the most common form of cutaneous mastocytosis presenting as reddish-brown monomorphic maculopapules, plaques or nodules appear in asymmetrical distribution anywhere on the body except the face, head, palms and soles. They uicate within a fewminutes of gentle rubbing (Darier's sign) & subsides within an hour. Telangiectasia macularis eruptiva perstan is a form ofcutaneous mastocytosis in adults presenting with red, telangiectatic macules, especially on the trunk, which tend not to uicate on rubbing. Other forms are mastocytoma & diffuse cutaneous mastocytosis. NB: darier's sign is also positive in juvenile xanthogranuloma and acute lymphoblastic leukaemia of neonates. Ref: Rook's textbook of dermatology, Edition-8, Page-22.31-32.", 'role': 'assistant'}]