The risk of progression among patients with atypical CLL phenotype MBL or non-CLL phenotype MBL is less well defined. For rare individuals with a phenotype and cytogenetic studies suggestive of mantle cell lymphoma or another aggressive NHL subtype but without adenopathy on CT scanning or substantial marrow involvement on marrow biopsy, we suggest clinical follow-up every 3–6 months with CT imaging at least every 6 months.(34) For those patients with atypical CLL phenotype MBL or non-CLL phenotype MBL whose immunophenotype is consistent with a more indolent NHL subtype (e.g. marginal zone lymphoma, follicular lymphoma), follow-up by a hematologist/oncologist every 6–12 months is recommended. The frequency of follow-up imaging requires clinical judgment and must be balanced with the risks associated with radiation exposure.(35)
