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: Pathology
[{'content': 'Malignant transformation to melanoma is common in: March 2009 \nSelect and explain. \nA. Dermal nevus, B. Junctional nevus, C. Congenital nevus, D. Lentigo nevus', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B: Junctional nevus Intradermal nevus: Benign; Junctional nevus: Premalignant: source for most malignant melanomas; looks like intradermal nevus but larger, often ulcerated, irregular border and heterogeneous coloration. Suspect melanoma if junctional nevus is getting darker or larger or bleeding or itching. Spitz nevus/spindle and epithetliod cellnevus is a red-pink nodule; often confused with hemangioma clinically Blue nevus is black-blue nodule; often confused with melanoma clinically', 'role': 'assistant'}]