Background and aim: The incidence of extra nodal non Hodgkin lymphoma (ENL) is rising throughout the world. However, data regarding ENL as a group is limited. The aim was to study the epidemiological and histomorphological trends of primary ENL (pENL) in India.
Material and methods: The biopsy materials from sixty eight patients with pENL (45 male, 23 female, M:F= 1.9:1), diagnosed over a five year period (2005-2009), were analysed and pathologically reclassified according to the World Health Organization (WHO) classification, 2008 criteria.
Results: Primary extra nodal non Hodgkin lymphomas constituted 22.0% (68/308) of all non Hodgkin lymphomas (NHL). The mean age at presentation for pENL and primary nodal NHL was 43 years and 58 years, respectively with a male predilection (M: F=2:1). Central nervous system (CNS) constituted the most common extranodal site (20/68, 29.5%) followed by gastrointestinal tract (17/68, 25%), and nose/nasopharynx (8/68, 11.8%). Diffuse large B-cell lymphoma (DLBCL, not otherwise specified), extranodal marginal lymphoma of mucosa associated lymphoid tissue (MALT) type, and B cell NHL unclassified (U) were the three most common histological types observed. T-cell phenotype was rarely noted (4%). Follicular lymphomas and anaplastic large cell lymphoma, seen among nodal NHL, were absent at extra nodal sites. Majority (41/68, 60%) of the patients with pENL were immunocompetent and 55% were in stage I-II with favorable prognosis.
Conclusion: Central nervous system was the most common site of ENL, followed by gastrointestinal tract. Majority of pENL occurred in immunocompetent hosts with a favorable prognosis.