input: The following are multiple choice questions (with answers) about medical knowledge.   **Question:** Elderly female present with pain and swelling in the thigh. Xray shows multiple lytic lesions in distal femur with no periosteal reaction. Aspirate from the swelling shows homogenous serosanguinous fluid with RBCs. Which investigation can confirm the diagnosis?   (A) S. Calcium levels   (B) S. PTH levels   (C) MRI   (D) CD1a IHC
output: ['(B) S. PTH levels <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) S. Calcium levels  (B) S. PTH levels  (C) MRI  (D) CD1a IHC <> possible answers', '  Elderly female present with pain and swelling in the thigh. Xray shows multiple lytic lesions in distal femur with no periosteal reaction. Aspirate from the swelling shows homogenous serosanguinous fluid with RBCs. Which investigation can confirm the diagnosis? <> context']