This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bone Tumour, Subject name: Orthopaedics
[{'content': 'A middle-aged female present with lytic lesion in lower 1/3 of femur. Biopsy showed grooved nuclei and giant cells. No periosteal reaction seen. What is the confirmatory investigation for this case:- \nSelect and explain. \nA. Serum PTH, B. Serum Calcitonin, C. Cd1a and Langerin IHC, D. MRI', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. (C) Cd1a and Langerin IHC(Ref: Apley's system of Orthopedics and Fracture 9th Ed; Page no-198 and 204)The possible diagnosis in the given scenario is Langerhans cell histiocytosis (LHC).Femur can be involved in LCH.LANGERHANS cells have a single large nucleus with characteristic folded or grooved nucleus (Coffee-Bean appearance) with small inconspicuous nucleoli.Visualization of the CD 1a surface marker is now considered sufficient to establish the diagnosis of LCH.", 'role': 'assistant'}]