Non-Hodgkin lymphomas – T cell type: Histomorphology and immunohistochemistry

Introduction: Non-Hodgkin lymphomas (NHL) comprise a wide variety of neoplasms and are subdivided into two main categories of low grade and high grade lymphomas. The major subtypes among T cell lymphomas are Peripheral T cell lymphomas – Not otherwise specified, Anaplastic Large cell lymphoma, ALK positive, Angioimmunoblastic T-cell lymphoma, T lymphoblastic leukemia/lymphoma and Extranodal NK/T cell lymphoma, nasal type. In this study, the histomorphological diagnostic features and the adjunct immunohistochemical expression of various markers are studied in a tertiary care centre in South India. Materials and Methods: Patients with lymphadenopathy over a period of two years were included in the study. Lymph nodes excised from these patients were routinely processed and examined. After initial examination with H&E stain, appropriate special stains like Reticulin stain, Periodic Acid Schiff stain and Ziehl-Neelsen stains are performed along with the specific Immunohistochemical markers. Results: A total of 30 cases were classified as Non-Hodgkin Lymphoma, high grade, T cell type. Peripheral T cell lymphomas-NOS is found to be the most common tumors accounting for 40% of all high grade T cell NHLs. The next common tumor was Anaplastic Large Cell Lymphoma, ALK positive with 36% of cases. T lymphoblastic leukemia/lymphoma accounted for 10% of cases and the rest of the cases were reported as Angioimmunoblastic T-cell lymphoma (7%) and Extranodal NK/T cell lymphoma, nasal type (7%). Conclusion: Appropriate use of immunohistochemistry aids in the sub-classification of lymphomas according to the recommendations of WHO 2008. But, further molecular studies should be performed for confirmation of the subtyping done by immunohistochemistry.