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
Which of the following is a marker for Langerhans cell histiocytosis? 
Select and explain. 
A. CD 1a, B. CD 10, C. CD 30, D. CD 56
A: CD 1a
Answer: A: CD 1a 
Explanation: The proliferating Langerhans cells in Langerhans cell histiocytosis are HLA-DR positive and express the CD1 antigen. Ref: Robin's Basic Pathology, 7th Edition, Page 441.