Central Nervous System Progression/Relapse in Mature T- and NK-Cell Lymphomas

The CNS relapse in T-cell lymphoma index predicts CNS relapse in patients with T- and NK-cell lymphomas

ABSTRACT

Little is known about risk factors for central nervous system (CNS) relapse in mature T-cell and natural killer cell neoplasms (MTNKNs). We aimed to describe the clinical epidemiology of CNS relapse in patients with MTNKN and developed the CNS relapse In T-cell lymphoma Index (CITI) to predict patients at the highest risk of CNS relapse. We reviewed data from 135 patients with MTNKN and CNS relapse from 19 North American institutions. After exclusion of leukemic and most cutaneous forms of MTNKNs, patients were pooled with non-CNS relapse control patients from a single institution to create a CNS relapse-enriched training set. Using a complete case analysis (n = 182), including 91 with CNS relapse, we applied a least absolute shrinkage and selection operator Cox regression model to select weighted clinicopathologic variables for the CITI score, which we validated in an external cohort from the Swedish Lymphoma Registry (n = 566). CNS relapse was most frequently observed in patients with peripheral T-cell lymphoma, not otherwise specified (25%). Median time to CNS relapse and median overall survival after CNS relapse were 8.0 and 4.7 months, respectively. We calculated unique CITI risk scores for individual training set patients and stratified them into risk terciles. Validation set patients with low-risk (n = 158) and high-risk (n = 188) CITI scores had a 10-year cumulative risk of CNS relapse of 2.2% and 13.4%, respectively (hazard ratio, 5.24; 95% confidence interval, 1.50-18.26; P = .018). We developed an open-access web-based CITI calculator (https://redcap.link/citicalc) to provide an easy tool for clinical practice. The CITI score is a validated model to predict patients with MTNKN at the highest risk of developing CNS relapse.

Intraoperative pathologic diagnosis of central nervous system lymphomas: A comparison of frozen and permanent section diagnoses, and the significance of preoperative imaging

BACKGROUND

Central nervous system (CNS) lymphomas, either primary or secondary in origin, are rare malignant tumors affecting the brain, spinal cord, or leptomeninges. Diagnosis of CNS lymphomas is complicated by their diverse clinical presentations, radiological features, and histopathological characteristics. Although frozen section (FS) analysis is commonly employed for various CNS tumors, its role and accuracy in CNS lymphoma diagnosis are less explored. In this study, we conducted a comparative analysis to assess the impact of knowledge of preoperative imaging on enhancing the accuracy of FS diagnosis in CNS lymphomas.

METHODS

Data collection involved a retrospective review of CNS lymphoma patients from January 2009 to August 2021. Patients who underwent intraoperative consultation were included, excluding those with prior cortisone treatment. The dataset incorporated patient demographics, classification as primary or secondary lymphoma, radiological preliminary diagnoses, FS diagnosis, and permanent section diagnosis. We employed various archived materials, including FSs, touch imprint slides, crush cytology slides, H&E-stained sections, and immunohistochemical stains, and re-evaluated all slides for diagnostic validation.

RESULTS

Our study included 25 patients, of whom 60 % were female and had a mean age of 56.5 years. Preoperative radiology data were available for 80 % of cases, with preliminary diagnoses commonly including lymphoma and/or metastasis. Intraoperative consultation results indicated lymphoma in 18 (72 %) patients, with discordance observed in 28 % of cases when compared to permanent section diagnoses. Most permanent section diagnoses were diffuse large B-cell lymphomas (92 %), with the remainder being T-cell non-Hodgkin lymphoma (4 %) and follicular lymphoma (4 %). Intraoperative misdiagnoses were significantly associated with the absence of knowledge of preoperative imaging.

CONCLUSION

Our study demonstrates the reliability of FS diagnosis for CNS lymphomas during surgery, with a favorable complete concordance rate of 72 % when compared to permanent diagnoses. Importantly, lack of knowledge of preoperative imaging significantly impaired diagnostic accuracy in FS, emphasizing the need for close collaboration between pathologists and radiologists.

Central Nervous System Relapse in T and NK cell Lymphomas

PURPOSE OF REVIEW

T and NK cell lymphomas are relatively rare and heterogeneous forms of non-Hodgkin lymphoma that are associated with high rates of mortality. Central nervous system relapse carries significant morbidity, though management is largely extrapolated from literature in B cell neoplasms. As such, outcomes for central nervous system involvement in T/NK cell lymphomas are dismal with no standard of care. In this review, we discuss the epidemiology of central nervous system relapse in T/NK cell lymphomas and critically analyze available literature regarding prophylaxis and treatment.

RECENT FINDINGS

Retrospective studies of central nervous system involvement in T/NK cell lymphomas have been limited by small sample sizes and heterogeneity of subtypes, though sites of extranodal involvement and disease subtypes are consistently reported as risk factors. Compelling evidence for the use of central nervous system-directed prophylactic therapy has not yet been established, though recent reports of central nervous system activity with novel agents may suggest promising therapeutic options. The overall rarity of T and NK cell lymphomas has precluded adequate study of prophylaxis and treatment of central nervous system relapse. Collaborative efforts are needed to better define strategies to address CNS disease in T/NK cell lymphomas. These should involve the use of targeted agents, which may hold an advantage over traditional cytotoxic drugs.