Everyone get this one? One of the old school differentials.

Answer: Ivory vertebral body (normal size but diffusely white/sclerotic)

DDX:

metastatic disease, especially carcinoma of the prostate or breast

Paget disease (not the classic presentation of Paget’s)

lymphoma, particularly Hodgkin lymphoma (look for soft tissue mass)

rare: carcinoid

Nice full write-up: http://radiology.rsna.org/content/235/2/614.long