This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology and Rheumatology, Subject name: Medicine
[{'content': 'What is the most likely diagnosis in this 50-year-old woman? \nSelect and explain. \nA. Metastasis, B. Onychomycosis, C. Psoriasis, D. Thromboangiitis obliterans', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer A. MetastasisFollowing radiography that revealed a lytic lesion of the terminal phalynx, the firm 2-cm lesion with a scab in the center was biopsied and found to represent a metastasis from follicular thyroid carcinoma.', 'role': 'assistant'}]