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
Postherpetic neuralgia is defined as pain lasting beyond how many weeks? 
Select and explain. 
A. 1 week, B. 2 weeks, C. 3 weeks, D. 4 weeks
D: 4 weeks
Answer: D: 4 weeks 
Explanation: Ans: D. 4 weeks(Ref Fitzpatrick 6/e p2302, 7/e p490-493, 1873-1898; Rooks 8/e p33.14-33.22; Roxburgh 18/e p52-54).Post-herpetic neuralgia (PHN):Most common & impoant neurologic complications of herpes zoster.Defined as pain after the rash has healed or pain 1 month or 3 months after rash onset.Best answer would be 4 weeks.