Soru

During a routine outpatient clinic visit, a $58$-year-old male patient reports a $2$-month history of progressive, deep, aching pain in his shins and wrists. He also describes worsening generalized fatigue and a $4\text{-kg}$ ($9\text{-lb}$) weight loss over the same period. He has a $30\text{-pack-year}$ smoking history and has not seen a physician in over a decade. Vital signs, including oxygen saturation on room air, are within normal limits. On physical examination, there is pronounced clubbing of the fingers and toes. There is bilateral, symmetrical, warm swelling of the wrists, metacarpophalangeal joints, and ankles. Deep palpation over the distal tibia and distal radius elicits exquisite periosteal tenderness. Cardiac auscultation reveals a regular rhythm with no murmurs, rubs, or gallops. Pulmonary examination demonstrates slightly decreased breath sounds at the right lung apex but is otherwise clear. Routine laboratory studies show a mild normocytic anemia and a borderline elevated rheumatoid factor of $24\text{ IU/mL}$ (normal $<20\text{ IU/mL}$). Based on this patient's specific constellation of physical examination findings, which of the following is the most appropriate next step in establishing the underlying diagnosis?