Image Description
B-cell transcription factor PAX5 is positive in more than 90% of classic Hodgkin lymphomas (cHL). The nuclear expression of PAX5 in Reed-Sternberg (RS) cells is usually weaker (see larger cells in the left half of the image) than in reactive B cells (right half).
Other transcription factors, including BOB1 and Oct2 are negative. If these two markers are strongly expressed, the diagnosis of B-cell lymphoma unclassifiable, with features between DLBCL and cHL should be considered.
IRF4/MUM1 is strongly positive in the nuclei of RS cells. It is also positive in anaplastic large cell lymphoma.
About the Disease
Classic Hodgkin lymphoma (cHL) is an uncommon malignant neoplasm of germinal-center B-cell origin that is primarily seen in young adults and, less commonly, in elderly patients. It usually arises in a single node or group of nodes and shows orderly spread to contiguous lymphoid tissues. The neoplastic cells - known as Hodgkin and Reed-Sternberg cells - make up only about 1% of all the cells in the involved lymph node or tissue. They express cell surface CD30 antigen and are present in a microenvironment rich in immune effectors cells. Four histologic subtypes are recognized in the current classification - nodular sclerosis, mixed cellularity, lymphocyte-rich, and lymphocyte-depleted. In about 5% of cases, a subtype cannot be specified due to insufficient material for a complete analysis. The prevalence of Epstein-Barr virus and its role in the pathogenesis depends upon the subtype. cHL is highly sensitive to radiation and chemotherapy and is characterized by a high cure rate, even in advanced stages. Several novel therapies targeting specific molecular pathways have been developed to treat refractory cases. The comments accompanying the images have been derived from the following sources: References:Jaffe, E. S. et al (2017). Hematopathology - Second Edition. Philadelphia, PA. Elsevier. Goldblum, J. R. et al (2018). Rosai and Ackerman's Surgical Pathology - 11th Edition. Philadelphia, PA. Elsevier. Kumar, V., Abbas, A. K., & Aster, J. C. (2021). Robbins and Cotran Pathologic Basis of Disease - Tenth Edition. Philadelphia, PA. Elsevier. Connors, J. M. et al. Hodgkin Lymphoma. Nature Reviews. Disease Primers (2020) 6:61. Kuppers R, Engert A, & Hansmann M. Hodgkin Lymphoma. J Clin Invest. 2012; 122(10):3439-3447.