A 59-year-old man, who underwent allogeneic liver transplantation for hepatitis B virus-associated hepatocellular carcinoma 1 year prior, showed multiple lymphadenopathy on CT scans. Submental lymph node biopsy showed uniform hypercellular follicles packed with monotonous large round cells and loss of polirization (A). Inter- and intrafollicular areas included lymphoplasmacytic infiltrations (B). Most lymphoplasma cells contained prominent Dutcher bodies (C). CD138 staining revealed mildly increased mature plasma cells (D). Lymphoplasma cells showed Kappa light chain restriction on in situ hybridization (E, Kappa; F, Lambda) and IgM production (G). Both the Follicular lymphoma and lymphoplasma cells showed strong BCL-2 immunoreactivity (H), whereas BCL-6 immunoreactivity was restricted to follicular lymphoma cells but negative in lymphoplasma cells (I). IgH and IgK gene rearrangements showed B-cell clonality.. Follicular lymphoma with lymphoplasma cell differentiation was the diagnosis, rather than monoclonal post-transplant lymphoproliferative disorder (PTLD) according to the World Health Organization classification. Staging work-up revealed stage 4 disease with bone marrow involvement. He received CHOP treatment with complete resolution. Follicular lymphoma in patients with the history of transplantation is not regarded as a PTLD, but a sporadic lymphoma. The present cases illustrates that follicular lymphoma with extensive Dutcher body formation may mimicking lymphoplasmacytic lymphoma/CD138-negative plasma cell neoplasm, which would constitute part of the spectrum of PTLD.