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
Button hole sign is seen in: 
Select and explain. 
A. Lupus vulgaris, B. Intertigo, C. Neuro fibromatosis, D. Psoriasis
C: Neuro fibromatosis
Answer: C: Neuro fibromatosis 
Explanation: Due to defect in dermis, pressure on a neurofibroma gives a feeling of hole in dermis, which is called as Button hole sign.