Anterior and posterior whole-body and spot pelvic images from a bone scan demonstrate a subtle round cold defect in the right iliac wing (circle).

Differential Diagnosis

•  Lytic metastasis: Renal cell metastases are commonly lytic and therefore cold on bone scan, making this the most likely diagnosis, given the history.

•  Myeloma: Solitary plasmacytoma or multiple myeloma is also commonly lytic (cold) but less likely, given the history.

•  Acute bone infarct: Bone infarcts are usually cold if acute but are not generally seen in this location. Femoral heads and diaphyses are more typically involved.