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
All of the following are true about incontinentia pigmenti, except: 
Select and explain. 
A. Ocular involvement is seen in almost 100% cases and is typically unilateral, B. Avascularity of peripheral retina, C. Primary skin abnormality, D. X-linked dominant
A: Ocular involvement is seen in almost 100% cases and is typically unilateral
Answer: A: Ocular involvement is seen in almost 100% cases and is typically unilateral 
Explanation: Ocular involvement is seen in about 20-35 percent of the cases of incontinentia pigmenti but not in 100 percent cases as mentioned in the option. Incontinentia pigmenti is a X-linked dominant primary skin disease that leads to avascularity of the retina. Ref: Rook's Textbook of Dermatology 7th Edition, Pages 39.20-3.22; The Retinal Atlas By Lawrence A. Yannuzzi, Page 38