Summary: Mantle cell lymphoma (MCL) is a rare peripheral B‐cell lymphoma characterised by eventual relapse and progression towards a more aggressive disease biology. With the introduction of rituximab‐ and cytarabine‐based immunochemotherapy regimens, the prognosis of the disease has changed dramatically over the last two decades. To assess the real‐world survival of patients with MCL, we used a population‐based cohort of 564 patients with MCL who were diagnosed and treated between 2000 and 2020. Patient data were collected from seven Finnish treatment centres and one Spanish treatment centre. For the entire patient population, we report a 2‐year overall survival (OS) rate of 77%, a 5‐year OS of 58%, and a 10‐year OS of 32%. The estimated median OS was 80 months after diagnosis. MCL is associated with increased mortality across the entire patient population. Additionally, we assessed the survival of patients after MCL relapse with the aim of establishing a cut‐off point of prognostic significance. Based on our statistical analysis of survival after the first relapse, disease progression within 24 months of the initial diagnosis should be considered as a strong indicator of poor prognosis.

There is no consensus on treatment strategies for elderly patients with mantle cell lymphoma (MCL). In this prospective phase II study we investigated whether the poor outcome could be improved, with reasonable toxicity, by prolonging the immunochemotherapy. Ten cycles of alternating cyclophosphamide, doxorubicin, vincristine and prednisolone (CHOP)/cytarabine (AraC) with eight doses of rituximab (R) were given as induction. The potential synergism of intermediate-dose AraC and fludarabine was tested in cycles 6–8. Induction was followed by bimonthly rituximab maintenance for 2 years. The median age of the 60 included patients was 74 years, and the Mantle Cell Lymphoma International Prognostic Index (MIPI) was intermediate or high risk in 98% of the patients. The overall response rate was 95% (complete response/complete response unconfirmed 87%). The response of 11 patients improved with cycles 6–8 (R-fludarabine-AraC). Progression-free survival was 70% and overall survival 72% at 4 years, respectively. Treatment related mortality was 2%. Severe infections were rare, with only one grade 4 infection. More dose reductions were needed during fludarabine-containing courses as compared to R-AraC. In 20 patients a transient grade 4 neutropenia without severe infections was recorded during maintenance. In conclusion, elderly patients with MCL can be treated relatively intensively with acceptable toxicity.

Aim: The purpose of the study was to evaluate the clinical impact of fluorodeoxyglucose‐positron emission tomography/computed tomography (FDG‐PET/CT) followed by a new biopsy from the site with maximum standardized uptake value (SUVmax) in case of high maximal SUV values, in detecting clinically unsuspected histologic transformations (HT) of follicular lymphoma (FL).Methods: This retrospective study included all the patients who had undergone FDG‐PET/CT during primary diagnosis or relapse of FL between 2010 and 2020 at Oulu University Hospital.Results: The diagnosis changed from an indolent disease to a transformed lymphoma in >10% (7/63) of the patients who underwent diagnostic FDG‐PET/CT. The HT risk associated with high SUVmax (>10) was 24% (7 of 29 performed biopsies). Four out of these seven patients with verified HT had no previous clinical suspicion of transformation.Conclusion: Our results suggest that a rebiopsy based on a high SUVmax in diagnostic FDG‐PET/CT is valuable in detecting clinically unsuspected HT of FL.

Antithrombin III (AT III) in cerebrospinal fluid (CSF) has been suggested to have high specificity and sensitivity in separating primary central nervous system (CNS) lymphoma from other neurological conditions. We measured with ELISA CSF and serum AT III and albumin levels in 12 lymphoma patients with CNS involvement, 30 lymphoma patients without CNS involvement, and 41 patients with non-neoplastic neurological diseases. AT III immunostaining was also carried out, in lymphoma patients. Both CSF AT III and albumin levels were higher in lymphoma patients with CNS involvement. AT III/albumin ratio in CSF was the most sensitive and specific measure for diagnosis. Lowest it was in patients with known CNS lymphoma. Serum AT III levels were lower both in CNS lymphoma and systemic lymphoma. CSF AT III levels were shown to be higher in lymphoma patients with CNS involvement, when AT III/albumin ratios were lower. This was probably a result of lowered serum AT III levels, indicating that high levels of AT III in CSF might reflect only leakage of the blood–brain barrier. Thus, AT III fails to be a specific marker for diagnosis of lymphoma CNS involvement.

Immunodeficiency-associated primary CNS lymphoma (ID-PCNSL) represents a clinicopathologically distinct PCNSL subtype, for which large studies and prognostic models are lacking. To address this gap, the International PCNSL Collaborative Group conducted an international retrospective multi-center study, integrating clinical, radiological, and pathological data from 308 ID-PCNSL, diagnosed at 23 participating sites in 7 countries. Pre-existing immunodeficiency included administration of immunosuppressants for transplantation (41.2%) or autoimmunity (36.7%), and HIV infection (21.7%). All tumors were diffuse large B-cell lymphomas, with Epstein-Barr virus (EBV) detected in 79.2%. Immune reconstitution together with rituximab-methotrexate-(RM)-based chemotherapy was associated with highest response rates and prolonged progression-free survival, irrespective of immunodeficiency subtype and EBV status. Survival outcomes were highly variable with a 54-month median overall survival. Multivariable Cox regression identified age (per year increment HR: 1.05 (95%-CI:1.02-1.07); p < 0.001), Karnofsky Performance status (KPS) < 70 (HR: 3.10 (95%-CI:1.67-5.87); p < 0.001), EBV positivity (HR: 3.26 (95%-CI:1.47-7.33); p = 0.004) as prognostic factors for OS. A prognostic score was developed based on the sum of these adverse variables (age > 60 years, KPS < 70, EBV positivity). Stratification by this score yielded median survival times of 135, 29, and 3 months in patients with up to one, two and three unfavorable markers (p < 0.0001). It allowed improved prognostic stratification of ID-PCNSL as compared to the well-established MSKCC and IELSG models developed for immunocompetent PCNSL. Collectively, this large international cohort defines clinicobiologic features of ID-PCNSL and introduces an easily applicable prognostic system with potential to guide future management.