Case Report: Fibrin-associated large B-cell lymphoma developing within a cystic lesion of the adrenal gland: unexpected guest.

Fibrin-associated large B-cell lymphoma (FA-LBCL) is recognized as a distinct entity in the 5th edition of the World Health Organization (WHO) classification of hematolymphoid tumors. It is a rare Epstein-Barr virus (EBV)-positive B-cell neoplasm that develops in areas of chronic fibrin deposition, associated with (pseudo)cystic cavities, long-standing hematomas, myxomas, or prosthetic devices. Cystic lymphangiomatous lesions of the adrenal gland are uncommon. Benign lymphovascular abnormalities are typically asymptomatic, but can be detected incidentally and removed to exclude other conditions. This report describes an exceptionally rare case involving a 42-year-old woman diagnosed incidentally with FA-LBCL arising within cystic lymphangiomatous lesions of the adrenal gland. We present a detailed account of the cytomorphological, immunohistochemical, and molecular characteristics of this FA-LBCL case and provide a concise overview of this emerging lymphoma subtype.