Review Question - QID 210860

A 55-year-old man presents to his primary care physician for fatigue. He states he has not felt like himself recently and had to take a few days off of work secondary to fatigue. He has lost 10 pounds over the past month. He drinks 4 drinks per day and smokes 1 pack of cigarettes per day, which he has done for the past 20 years. His temperature is 99.0°F (37.2°C), blood pressure is 128/65 mmHg, pulse is 100/min, respirations are 11/min, and oxygen saturation is 98% on room air. Laboratory values are ordered as seen below.

Hemoglobin: 9 g/dL
Hematocrit: 27%
Leukocyte count: 2,500/mm^3 with normal differential
Platelet count: 93,000/mm^3

A biopsy of the bone marrow is performed which demonstrates hypocellular and fibrotic bone marrow and a peripheral smear is performed as seen in Figure A. Which of the following is the most likely diagnosis?