74-year-old man comes to the physician because of a trouble climbing one flight of stairs due to lower extremity pain. The pain feels dull and achy and is worsened by movement, causing him to have difficulty bearing weight and ambulating. He has hypertension and takes hydrochlorothiazide. Physical examination shows tenderness to palpation over the lower extremity. There is pedal edema. Laboratory studies show a hemoglobin concentration of 8.7 g/dL, a serum creatinine concentration of 2.3 mg/dL, and a serum calcium concentration of 12.6 mg/dL. Urine dipstick is negative for blood and protein. A radiograph of the right lower extremity is shown in the exhibit. Which of the following is the most likely explanation for this patient's bone changes?

Question

74-year-old man comes to the physician because of a trouble climbing one flight of stairs due to lower extremity pain. The pain feels dull and achy and is worsened by movement, causing him to have difficulty bearing weight and ambulating. He has hypertension and takes hydrochlorothiazide. Physical examination shows tenderness to palpation over the lower extremity. There is pedal edema. Laboratory studies show a hemoglobin concentration of 8.7 g/dL, a serum creatinine concentration of 2.3 mg/dL, and a serum calcium concentration of 12.6 mg/dL. Urine dipstick is negative for blood and protein.   A radiograph of the right lower extremity is shown in the exhibit.   Which of the following is the most likely explanation for this patient's bone changes?

Quizplus · Accepted Answer

Eductional Objective: Multiple myeloma is a plasma cell malignancy associated with purely radiolucent (osteolytic) bone lesions due to the stimulation of osteoclasts and the inhibition of osteoblasts.  Myeloma cells stimulate osteoclast development by secreting RANK-ligand and destroying osteoprotegerin, which increases RANK activity and results in osteoclast differentiation.

74-Year-Old Man Comes to the Physician Because of a Trouble