Fluid-Overload Associated Large B-Cell Lymphoma Clinicopathologic Features and Determinants of Outcomes: Analysis of a Pooled Database

Background:

Fluid overload-associated large B-cell lymphoma (FOLBCL) is a new WHO lymphoma entity previously known as PEL-like lymphoma or HHV8-unrelated PEL-like lymphoma. It is a rare lymphoma that arises within fluid-filled body cavities without a solid component. FOLBCL occurs in the absence of immunodeficiency and is commonly associated with conditions associated with fluid overload. It expresses mature B-cell phenotype and occasional EBV infection markers. We conducted this study to delineate key clinicopathological characteristics, prognostic indicators, and treatment modalities that affect outcomes in this rare and newly-defined lymphoma subtype.

Methods:

To study the demographic characteristics, molecular and immunohistochemical signatures, therapeutic interventions, survival, and prognostic factors, we compiled a pooled database of 115 cases that fit the diagnostic criteria for FOLBCL. Kaplan-Meier survival curves were constructed. Cox proportional hazards model and Log-rank tests were used to assess the influence of demographic and clinicopathologic factors on overall survival (OS).

Results:

A total of 115 patients with confirmed FOLBCL were identified. The median age was 74, with a peak incidence between 72 and 82 years. There was a male preponderance with M:F of 2. The pleural, pericardial, and peritoneal cavities were involved in 75%, 34%, and 27%, respectively. The median duration of symptoms before diagnosis was 1 month. Patients presented with constitutional symptoms and hepatosplenomegaly in 13% and 1%, respectively-no patients presented with lymph node and bone marrow involvement. The median OS of the whole group was 16 months. Patients younger than 70 had better median OS than 70 and older (24 vs. 10 months, p=0.008). The presence of any malignant peritoneal effusion was associated with worse OS when compared to effusion limited to the thoracic cavity (7 vs. 24 months, p=0.005). LDH≥500 was also associated with worse OS (p=0.02). Sex, the presence of fluid overload-causing conditions, and serum IL2R levels did not seem to impact OS. Compared to no treatment, chemotherapy had a numerically superior OS but did not reach statistical significance (19 vs. 10 months, p=0.11). However, patients that attained CR as their best response had a superior median OS (p<0.0001).

Conclusions:

This study presents updated clinicopathologic data from a pooled cohort of patients with FOLBCL. It identifies the age, the primary location of cavitary disease, LDH, active therapy, and quality of response to treatment as key determinants of OS.