Review Question - QID 108671

A 74-year-old man is being evaluated for a 6 month history of fatigue. His past medical history is significant for childhood leukemia, rheumatoid arthritis, and coronary artery disease. His current medications include methotrexate, simvastatin, and aspirin. The patient has been living alone since his wife passed away 2 years ago and says that it has been hard because she was previously responsible for all the shopping and cooking in the family. He reports that he is not currently sexually active and has not had a recent STI test. His temperature is 98.6°F (37°C), blood pressure is 114/72 mmHg, pulse is 91/min, and respirations are 12/min. A physical exam reveals decreased vibratory sensation in the lower extremities bilaterally, positive Babinski sign, and ataxia. Laboratory tests are as follows:

Leukocyte count and differential:
Leukocyte count: 4,500/mm^3
Segmented neutrophils: 60%
Bands: 3%
Eosinophils: 2%
Basophils: < 1%
Lymphocytes: 26%
Monocytes: 7%
Hemoglobin: 11.2 g/dL
Platelet count: 112,000/mm^3
Mean corpuscular hemoglobin concentration: 33%
Mean corpuscular volume: 125 µm^3
Reticulocyte count: 0.8%
Lactate dehydrogenase: 470 U/L

A peripheral blood smear is shown in Figure A. Which of the following is related to this patient’s symptoms?