This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood, Subject name: Pathology
Beta-2 microglobulin is a marker for? 
Select and explain. 
A. Multiple Myeloma, B. Mycosis fungoides, C. B-Cell lymphoma, D. Mantle cell lymphoma
A: Multiple Myeloma
Answer: A: Multiple Myeloma 
Explanation: Ans. is 'a' i.e., Multiple myeloma * Serum b2 microglobulin is increased in multiple myeloma and is the most important prognostic factor and can substitute for staging.* b2 Microglobulin level:a) < .004g/L - Median survival of 43 months.b) .004 g/L - Median survival of only 12 months.