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
[{'content': 'Birbeck granules in the cytoplasm is seen in: \nSelect and explain. \nA. Langerhans cells, B. Mast cells, C. Myelocytes, D. Thrombocytes', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (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', 'role': 'assistant'}]