B2M and follicular lymphoma: As well-established prognostic factor, high serum beta-2 microglobulin is a component of the International Staging System (ISS) and Revised-ISS for multiple myeloma [12, 13, 22, 23] and one of the parameters of the follicular lymphoma international prognostic index 2, a proven prognostic model of follicular lymphoma in the rituximab era [14].