Extra Nodal Non Hodgkin’s Lymphomas using Immunohistochemistry from a Tertiary Care Centre, Andhra Pradesh, India- A Retrospective Study

Abstract

Introduction: Primary Extranodal Lymphomas (pENL) are a group of lymphomas arising from tissues other than lymph nodes and even sites which normally contain no lymphoid tissue. Over the past 25 years pENLs have shown a rapid increase in incidence. pENLs can originate from almost any anatomical site such as the gastrointestinal tract (most common), head and neck (waldeyer’s ring, nose/paranasal sinuses/nasopharynx, salivary glands, etc.,), skin, Central Nervous System (CNS) etc. The definition of Extranodal Lymphoma (ENL), particularly in the presence of both nodal and extranodal disease remains a controversial issue. To categorise these entities, different criteria were proposed by different authors. Aim: To study the occurrence of extranodal non hodgkin’s lymphomas in different sites/organs using Immunohistochemistry (IHC). Materials and Methods: This was a retrospective study carried out in the Department of Pathology, Sri Venkateswara Institute of Medical Sciences (SVIMS), Tirupati, Andhra Pradesh, India, over a period of 7 years 6 months starting from January 2010 to July 2017. Data was retrieved from the medical records and paraffin blocks were retrieved from the stores. All cases of extranodal primary lymphomas were included in the study. All cases were classified based upon morphologic and immunophenotypic criteria according to World Health Organisation (WHO) 2008 classification. The distribution of primary extranodal lymphomas among different age groups with mean age of occurrence was noted. Distribution of pENLs among male and female population with male to female ratio was calculated. The percentage of different sub-types of ENL and the Immunohistochemistry (IHC) markers in each subtype of ENL were calculated. Results: In this retrospective study, a total of 317 newly diagnosed lymphoma cases were included. Among them, 79 cases were pENL. A total of 77 (24.29%) cases of primary extranodal non Hodgkin’s lymphomas were included in the study. The age of the patients ranged from 4-81 years with mean age of 48.42 years, with male predominance (M:F-1.85:1). Gastrointestinal Tract (GIT) (35/77-45.45%) was the most common site, followed by head and neck (16/77-20.77%), mediastinum (4/77-5.19%), kidney (4/77-5.19%) were the common sites of occurrence of primary extranodal NHLs. In the GIT, stomach was the most commonly involved site (24/35) followed by the small intestine (5/35), colon and anal canal (3/35) and ileo-caecal region (3/35). The Diffuse Large B-cell Lymphoma (DLBCL) was the most common histological type observed in 51/77 (66.23%), followed by Peripheral T-cell Lymphoma- Not Otherwise Specified (PTLNOS) were observed in 14/77 (18.18%) cases, and extranodal marginal zone lymphoma of Mucosa-associated Lymphoid Tissue (MALT) type seen in 9/77 (11.68%) cases. Conclusion: pENLs are a diverse group of haemato-lymphoid malignancies, the incidence of which is low in India compared to rest of the world, the prognosis of which depends on the extranodal site. The diagnosis is challenging due to the morphological mimics and varied clinical presentation and that is