57-year-old man presented to his primary care physician with a 2-year history of progressive right hip pain. His medical history was notable for hyperlipidemia. He was up-to-date on sex- and agespecific cancer screening. The patient had no history of chest pain, palpitations, shortness of breath, cough, or other cardiac, respiratory, neurologic, or visual symptoms. He had no recent travel history or occupational or social contact with persons who were ill. Physical examination revealed an obese man (body mass index [calculated as weight in kilograms divided by height in meters squared], 40.34 kg/m 2 ) with normal vital signs and unremarkable findings on cardiac, respiratory, abdominal, neurologic, and lymphatic examination. No pain or tenderness was elicited on examination. He was treated initially with nonopioid pain medications. Sacroiliac corticosteroid injections were minimally beneficial. Results of a complete blood cell count (CBC) and electrolyte panel were normal with the exception of an elevated serum calcium level of 11.7 mg/dL (reference range, 8.9-10.1 mg/dL). Ultimately, magnetic resonance imaging (MRI) of his lumbar spine revealed numerous punched-out lytic lesions in the lumbar vertebra and pelvis. He underwent computed tomography (CT) of his chest, abdomen, and pelvis that identified further lytic lesions as well as multiple splenic lesions concerning for metastases. Two separate CT-guided bone biopsy samples of the lytic lesions in the lumbar vertebra did not elicit an etiology of the lesions.