Immunohistochemical (IHC) Analysis of Non-Hodgkin's Lymphoma (NHL) Spectrum According to WHO/REAL Classification: A Single Centre Experience from Punjab, India.

INTRODUCTION The distribution of the major subtypes of non-Hodgkin's lymphoma (NHL) differs across geographic regions. This study, from the north Indian state of Punjab, has incorporated immunophenotypic findings while investigating the distribution of NHL subtypes based on World Health Organization (WHO)/ Revised European-American Classification of Lymphoid Neoplasms (REAL) system of classification. PATIENTS AND METHODS Over all seventy seven cases of lymphoma over a period of one year (between April 2012 and April 2013) were diagnosed in the Department of Pathology, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar (Punjab). Of these 30 cases (39%) were of Hodgkin's Lymphoma (HL) and 47 cases (61%) were of Non Hodgkins lymphoma NHL. Of the total of cases of lympho-proliferative disorders, the diagnosis of NHL was done by light microscopy alone. All the cases diagnosed provisionally as NHL were taken up for immunophenotyping with Immunohistochemical (IHC) studies. There was 100 % concordance between the light microscopy and IHC studies. The individual NHL cases were classified according to the WHO/REAL classification according to the positive or relevant negative immonophenotypic expression and tabulated to ascertain the morphological spectrum of NHL in this part of the country. RESULTS B-cell lymphomas formed 89.3%, whereas T-cell lymphomas formed 10.7% of the NHLs. Diffuse Large B-Cell Lymphoma (DLBCL) was the most common subtype (46.8% of all NHLs). B-cell small lymphocytic lymphoma, Mantle-Cell Lymphoma (MCL), marginal zone B-cell lymphomas (including MALT lymphomas), Diffuse, mixed small cleaved cell and large-cell type and Follicular centre-cell lymphomas amounted to 17%, 12.8%, 2.1%, 2.1% and 4.3%, respectively. Among the T-cell lymphomas, T-cell lymphoblastic lymphoma, anaplastic large-cell lymphomas of T/null-cell type, and Angioimmunoblastic T-cell lymphoma (AITL) accounted for 6.4%, 2.1%, and 2.1% of all NHL cases, respectively. CONCLUSIONS The distribution of NHL subtypes in India shows disparity with those from the rest of the world. Follicular Lymphoma (FL) and MCL are less common in India compared to Europe and the USA. Peripheral T-cell lymphomas and T/NK-cell lymphomas of nasal and nasal types, which are common in many other Asian countries, are also less prevalent. T-cell lymphoblastic lymphoma and anaplastic large T/null cell lymphoma are more prevalent in India.