Right Arm Pain and Swelling in an End-Stage Kidney Disease Patient

### Case Description A 51-year-old man with ESKD secondary to FSGS on thrice weekly hemodialysis presented with an expanding painful right arm mass. He had long-standing secondary hyperparathyroidism with a persistently elevated PTH level > 2000 pg/ml and had been refusing to take calcimimetics or to undergo parathyroidectomy. Physical examination demonstrated a hard and tender mass on the lateral aspect of the humerus. An x-ray showed a 7.2×4-cm expanding lytic lesion with periosteal reaction (Figure 1). A skeletal survey showed similar smaller masses in the left humerus, left second metatarsal bone, and distal ulna together with few calcified soft tissue lesions in the right forearm, as well as partial Achilles tendon calcification and calcified abdominal aorta. A diagnosis …