What is the most likely diagnosis in a 75 year old?
Metastasis or multiple myeloma / plasmacytoma would be most likely.
Which metastases are classically expansile?
Classically renal cell carcinoma, thyroid cancer and less commonly hepatocellular carinoma. Occasionally the sclerotic metastases of prostate cancer may also be expansile and closely mimic Paget's disease of bone.
True or false: Skeletal metastases tend to have little if any periosteal reaction.
True. This is a helpful sign as many primary bone tumours have extensive periosteal reaction.
A large lytic and expansile lesion involves the medial third of the clavicle.