This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Lymphoma and Plasma cell disorder, Subject name: Medicine
In lymphoplasmacytoid lymphoma which of the following monoclonal immunoglobulin is seen? 
Select and explain. 
A. IgA, B. IgD, C. IgG, D. IgM
D: IgM
Answer: D: IgM 
Explanation: Lymphoplasmacytoid lymphoma /Waldenstrom's Macroglobulinemia. The majority of patients in this disease have monoclonal IgM serum para-protein. In contrast to myeloma, the disease was associated with lymphadenopathy and hepatosplenomegaly,but the major clinical manifestation was the hyperviscosity syndrome.