Fibrin-Associated Large B-Cell Lymphoma in a Young Patient in the Setting of Pleural Effusion

Abstract Introduction/Objective Fibrin-associated large B-cell lymphoma (FA-LBCL) is a proliferation of EBV-positive large B- cells in association with fibrinous debris, typically in the context of prostheses, hematomas, pseudocysts and myxomas. It is a newly described entity and is extremely rare, with no deaths reported as a direct result. It is indolent and not visible on imaging, instead being found incidentally on microscopy. It is mainly a diagnosis of exclusion and is characterized by sheets of neoplastic lymphocytes contained within a fibrin background. The median age of presentation is 55, with 75% of cases being reported among elderly patients. The prognosis is excellent and surgery is considered curative. It needs to be distinguished from malignant lymphomas, mainly diffuse large B-cell lymphoma associated with chronic inflammation (DLBCL-CI), which is also EBV-positive but occurs in elderly patients with a longstanding history of inflammation. The two have identical immunohistochemical profiles but vastly different clinical presentations and outcomes. Methods/Case Report A 35-year-old male with end-stage renal disease and a history of recurrent pleural effusions presented with dyspnea. CT showed a large loculated right-sided pleural effusion with no lymphadenopathy. Pleural fluid cytology was negative for any malignant cells. He underwent decortication to relieve pleural rind constriction. Microscopy revealed small layers of fibrin with an infiltrate of atypical, EBV-positive B-cells with a Ki-67 index of 60%. As the morphological findings and clinical presentation did not fit other known lymphomas, the case was signed out as FA-LBCL. The patient has followed up with oncology and PET scans have been negative for any malignancy. He is currently on the waiting list for a renal transplant. Results (if a Case Study enter NA) NA Conclusion FA-LBCL is a rare benign neoplasm, identified incidentally and cured by surgical resection. It is mainly diagnosed in the elderly, but the number of cases is limited and the age distribution may be skewed. This case involved a much younger patient and is the first known diagnosis in the pleural setting. It is important to differentiate this entity from DLBCL-CI, which is aggressive and requires intense oncological treatment. In addition, patients with FA-LBCL can undergo immediate solid organ transplantation, whereas those with DLBCL-CI need to be in remission for at least three years before receiving a transplant.