CLINICAL HISTORY
Two axillary lymph nodes of 1 cm diameter from a 28 year old female were sent for consultation. Her past medical history was significant for allogeneic bone marrow stem cell transplantation for aplastic anemia. She was on the 85th day of transplantation when the lymph node enlargement was noted.
Microscopic examination revealed a diffuse infiltration of plasma cells and small lymphocytes effacing the normal architecture of the lymph node (Figure 1). Necrosis and atypical cells were not present. Immunohistochemical studies highlighted residual B cell regions, expanded paracortical zones and plasma cell infiltration (Figure 2). Plasma cell infiltration was found to be polyclonal with immunohistochemical staining (kappa and lambda) (Figure 3).
Post-transplant lymphoproliferative disorder, as the name implies, is a heterogeneous group of lymphoid proliferations in the setting of immunosuppression in transplant patients. The Society of Haematopathology has classified these diverse lymphoproliferative disorders into hyperplastic, polymorphic and monomorphic (lymphomatous) PTLD groups. Reactive plasmacytic hyperplasia is regarded as early lesion of PTLD and is included in the hyperplastic PTLD together with “infectious mononucleosis” and “atypical lymphoid hyperplasia with architectural retention”. EBV virus is accused as an etiologic factor in majority of the PTLD. Lymph nodes and Waldeyer ring are involved. Morphologically, lymph node shows interfollicular hyperplasia composed of polyclonal plasma cell proliferation. This growth may contain one or several minor clonal subpopulations. The presence of EBV can be shown both immunohistochemically or by in situ hybridisation. These lesions usually regress following reduction of immunosuppressive therapy, but one should be aware that these rapidly proliferative lesions may behave in an aggressive fashion and result in death.
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