Diagnosis and immunocytochemical characterization of an EBV related diffuse B Large cell lymphoma of the retroperitoneum from cell block preparations obtained by means of EUS guided FNA.

Objective Primary retroperitoneal involvement of lymphoproliferative disorders is rare. Diffuse large B cell lymphoma (DLBCL) in the retroperitoneum has been scarcely reported and the diagnostic workup is challenging due to difficulties in access for tissue acquisition. Materials and methods A 73-year-old female presented with epigastric pain and nausea. A computed tomography scan revealed retroperitoneal lymphadenopathy. An EUS-FNA was performed and a cytological diagnosis of lymphomatous disorder was made on direct smears .A panel of immunocytochemical markers was applied on cell block preparations and revealed a EBV related DLBCL (CD20 positive, PAX-5 positive, CD3 negative, MUM-1 positive, BCL-2 positive, BCL-6 positive, CD10 positive, MIB-1 positive, and LMP-1 positive). Conclusion Our case illustrates the utility of EUS-FNA in the work-up of retroperitoneal lymphadenopathy and the importance of cell block processing in the diagnostic approach of EBV related DLBCL.