Blastoid
mantle cell lymphoma is characterized by highly aggressive features and a dismal
clinical course. These blastoid and pleomorphic variants are defined by cytomorphological features, but the criteria are somewhat subjective. The diagnosis may be supported by a high cell proliferation based on the Ki-67 labeling index. Recent analyses have shown that the Ki-67 index overrules the prognostic information derived from the cytology subtypes. Nevertheless, genetic analysis suggests that blastoid and pleomorphic variants are distinct from classical
mantle cell lymphoma. In clinical cohorts, the frequency of these subsets varies widely but probably represents ∼10% of all cases.
Chemotherapy regimens commonly used in
mantle cell lymphoma, such as
bendamustine, rarely achieve prolonged remissions when given at the dosage developed for classical variants of the disease. Thus, high-dose
cytarabine-containing regimens with high-dose consolidation may be generally recommended based on the more aggressive
clinical course in these patients. However, even with these intensified regimens, the long-term outcome seems to be impaired. Thus, especially in this patient subset,
allogeneic transplantation may be discussed at an early time point in disease management. Accordingly, targeted approaches are warranted in these patients, but clinical data are scarce.
Ibrutinib treatment results in high rates of responses, but the median duration of remission is <6 months. Similarly,
lenalidomide and
temsirolimus result in only short-term remissions. Novel approaches, such as chimeric antigenic receptor T cells, may have the potential to finally improve the dismal long-term outcome of these patients.