This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood, Subject name: Pathology
Birbeck granules in the cytoplasm is seen in: 
Select and explain. 
A. Langerhans cells, B. Mast cells, C. Myelocytes, D. Thrombocytes
A: Langerhans cells
Answer: A: Langerhans cells 
Explanation: (Langerhans cells): Ref: 701-702-R, 463-HM (467-Basicpathology tfh)* The presence of Birbeck granules in the cytoplasm is characteristic of Langerhans cell histiocytosis (Tennis- rachet appearance)* As Birbeck granules are not seen in all tumours cells by electron microscopy the detection of 5-100 and CDla expression by immuno histochemical techniques aids in the diagnosis