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: Dental
A child presents with a solitary white well-defined patch on his right thigh. Diagnosis is – 
Select and explain. 
A. Piebaldism, B. Albinism, C. Nevus achromicus, D. Acral vitiligo
C: Nevus achromicus
Answer: C: Nevus achromicus 
Explanation: Information is this question are :-


Lesion is on thigh
Unilateral lesion (Isolated lesion on Right thigh)


Both these suggest Nevus achromicus, i.e. Nevus acromicus involves :-


Trunk and proximal extremity (thigh in this question)
Lesion is unilateral


Also keep in mind that, though Nevus achromicus presents since birth, it may be missed at birth and the patient may present in childhood