This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hemolytic Anemias: Basic concepts and classification, Subject name: Pathology
All of the following are pre-leukemic conditions except 
Select and explain. 
A. Paroxysmal nocturnal hemoglobinuria, B. Paroxysmal cold hemoglobinuria, C. Aplastic anemia, D. Myelodysplastic syndrome
B: Paroxysmal cold hemoglobinuria
Answer: B: Paroxysmal cold hemoglobinuria 
Explanation: - Paroxysmal cold hemoglobinuria aka cold hemolysin disease is associated with cold AIHA (Auto Immune Hemolytic Anemia). Its not pre-leukemic condition. Special antibody seen in this condition is Donath-Landsteiner Ab against P antigen. Most cases are seen in children following viral infections; in this setting the disorder is transient, and most of that affected recover within 1 month. - Remaining all conditions given in options are pre-leukemic conditions.