Review Question - QID 213611

A 67-year-old woman presents to the emergency department with back pain. The patient states that her back pain started while she was trying to move a heavy piece of furniture. She endorses recent weight loss of 5 pounds and fatigue over the past 2 months. The patient has a past medical history of osteoporosis, HIV on HAART therapy, hot flashes, depression, and anxiety and has a 40 pack-year smoking history. She admits to doing heroin regularly. Her temperature is 99.8°F (37.7°C), blood pressure is 147/98 mmHg, pulse is 100/min, respirations are 17/min, and oxygen saturation is 98% on room air. Physical exam is notable for tenderness over the patient’s midline spine with palpation as well as tenderness over the paraspinal muscles with symptoms worsened by flexion. A radiograph is ordered as seen in Figure A. Laboratory values are ordered as seen below.

Serum:
Na+: 139 mEq/L
Cl-: 100 mEq/L
K+: 4.3 mEq/L
HCO3-: 25 mEq/L
BUN: 20 mg/dL
Glucose: 99 mg/dL
Creatinine: 1.4 mg/dL
Ca2+: 10.2 mg/dL

Which of the following is the most likely diagnosis?