Image Description
The nodal architecture in angioimmunoblastic T-cell lymphoma is effaced by a polymorphic infiltrate occupying the interfollicular or paracortical areas of the node. The infiltrate consists of small to medium-sized lymphocytes (neoplastic cells) admixed with neutrophils, eosinophils, plasma cells, dendritic cells, histiocytes, and epithelioid cells.
In some cases, the epithelioid cells are quite prominent (as seen in this example) and may mask the key diagnostic features. The epithelioid cells are present in a background of small to medium-sized neoplastic T-cells and a few basophilic blast-like cells.
About the Disease
Angioimmunoblastic T-cell lymphoma (AITL) is a type of peripheral T-cell lymphoma arising from follicular helper T cells of the germinal center. It is a systemic disease that presents with generalized lymphadenopathy, hepatosplenomegaly, constitutional symptoms, skin rash, anemia, and polyclonal hypergammaglobulinemia. There is effacement of the normal nodal architecture with disappearance of follicles and germinal centers, a polymorphic cellular infiltrate that extends into perinodal tissues, and proliferation of high endothelial venules and follicular dendritic cells. The atypical T-cells have irregular nuclei and clear cytoplasm. Epstein-Barr virus (EBV) can be detected by in-situ hybridization in 80% to 90% of lymph nodes affected by AITL. The virus is present in transformed B-cells and is not considered to play a role in the pathogenesis. The T-cell receptor genes are clonally rearranged. AITL is a rapidly progressive disease with a median survival of under 3 years. Given the abnormal T-cell function and the immunodeficient state, the cause of death in most cases is complications from infectious diseases. Many patients with AITL also develop EBV+ diffuse large B-cell lymphoma. References:Jaffe, E. S. et al (2017). Hematopathology - Second Edition. Philadelphia, PA. Elsevier. Swerdlow S. H. et al (2017). WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues. Revised 4th Edition. Lyon, France.