A 45-year-old woman presents to the emergency department with fatigue, shortness of breath, and jaundice. Laboratory results show severe anemia (hemoglobin 6.5 g/dL), elevated indirect bilirubin, and lactate dehydrogenase (LDH). Her peripheral blood smear shows spherocytes and polychromatic red cells. A direct Coombs test is positive for IgG. What is the most likely diagnosis?
