`DIAGNOSTIC PITFALLS IN THE INTERPRETATION OF EXTRANODAL LYMPHOMAS – A CASE SERIES

Abstract

Extranodal non-Hodgkin’s lymphoma (ENNHL) by definition affects any organ or tissue excluding lymph node and spleen. Histopathological examination is the investigation of choice that further helps in deciding the advanced diagnostic panel of the immunohistochemistry (IHC) and molecular studies. Histopathological evaluation as such is not straight forward, since there is high probabilty of misdiagnosis and diagnostic pitfalls due to inadequate material, sampling and processing errors, inadequate clinical information, personal subjectivity of clinicians and pathologists, and IHC-related errors. This case series is reported at a tertiary care hospital. Total three cases of ENNHL are reported, where the process of diagnosis went through few pitfalls before the ultimate diagnosis was made. The first case was a jejunal mass clinically diagnosed as carcinoma, histopathologically found to be extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue transforming to diffuse large B-cell lymphoma in the mesenteric lymph node. Second case describes misinterpretation of small lymphocytic lymphoma as adenocarcinoma deposit in liver by clinical and radiological evaluation. Third case describes follicular dendritic cells of spleen where the first two biopsies showed chronic lymphocytic gastritis and reactive lymphadenitis and finally the third from spleen confirmed the diagnosis. The diagnosis of ENNHL in biopsies requires clinicopathological suspicion with discussion and repeat biopsies if inconclusive. Pathologist should be aware of the gross and microscopic features indicating high-grade NHL transformation in surgical specimens. During the initial clinical evaluation and follow-up of low-grade ENNHL, positron emission tomography scan findings can be used, to effectively target biopsy from areas or regional lymph nodes suspicious of high-grade transformation.