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Answers on p 743.
A 27 year old woman presented in the third trimester of pregnancy with a history of gradually progressive pain in the upper end of her humerus. There was no significant medical history or any other associated illness. Magnetic resonance imaging (MRI) revealed a pathological fracture with extensive marrow replacement of the upper humerus and an associated large soft tissue mass in the upper arm (fig 1). A core needle biopsy documented benign giant cells. The patient was treated with excision and replacement with a prosthesis.
What is the differential diagnosis based on the history and the MRI (giant cell tumour, brown tumour, chondrosarcoma, secondaries in the bone)?
What other relevant blood investigation should be ordered in such patients (calcium, parathyroid hormone, alkaline phosphatase, acid phosphatase)?