Endoscopic Ultrasound-Guided Fine Needle Aspiration Biopsy for Diagnosis of Intra-Abdominal Lymphoma without Accessible Peripheral Lymphadenopathy

Introduction: Endoscopic ultrasound-guided fine needle aspiration biopsy (EUS-FNAB) is considered the procedure of choice for the diagnosis and staging of intra-abdominal non-Hodgkin’s lymphoma (NHL) without accessible peripheral lymphadenopathy. However, diagnosis and subclassification lymphoma by FNAB is often challenging due to variable cellularity and lack of architecture. Recent advances of ancillary techniques such as immunohistochemical staining, flowcytometry (FCM), fluorescence in situ hybridization (FISH) analysis and molecular analysis allowed classify lymphoma more precisely, although sufficient information can be obtained through this procedure remained undetermined. The present study was performed to evaluate the yield of EUS-FNAB using a standard 19 or 22-gauge needle for diagnosis and subclassification of lymphoma, assessing the feasibility of immunohistological, FCM, molecular and cytogenetic assessments.

Methods: Between April 2008 and July 2014, 90 patients with malignant lymphoma who had an intra-abdominal mass without accessible peripheral lymphadenopathy underwent EUS-guided fine needle aspiration biopsy at our hospital. All patients received positron emission tomography/computed tomography and had 2-deoxy-2-(¹⁸F)fluoro-D-glucose-avid lesions in abdomen before examination. The aspirated materials were processed for flowcytometry (FCM), molecular analysis of immunoglobulin heavy (IgH) and T-cell receptor (TCR) gene rearrangement, cytogenetic analysis by conventional G banding, and FISH analysis, in addition to standard histopathological studies. Patients’ baseline data, including age, sex, laboratory examinations, imaging studies, and final diagnosis of lymphoma, were collected and examined to determine the feasibility and sensitivity for diagnosis and subclassification of lymphoma.

Results: The mean of the diameter of mass was 37mm (9.7-149mm). Among the 90 patients, conventional G banding, FCM analysis, standard cytogenetic analysis, and FISH were successfully performed in 67 (74%), 78 (87%), 44 (49%), and 58 (64%) cases, respectively. G banding analysis were successful in 45 patients (67%) that showed normal karyotype in 5 cases (7%), t(14;18)(q32;q21) in 7 cases (10%), t(8;14)(q24;q32) in one case, and complex abnormality in 32 cases (48%), respectively. FCM analysis showed immunoglobulin light chain restriction in 48 cases (62%) and were diagnosed as B-cell lymphoma. FCM could not determine the T-cell clonality. Molecular analyses for TCR and/or IgH receptor rearrangements were successful in 35 patients (83%), 31 rearranged in IgH and 4 rearranged in TCR, respectively. There were 32 cases with IgH/Bcl2 fusions by FISH analysis, 26 cases in follicular lymphoma (FL) and 6 cases in diffuse large B-cell lymphoma (DLBCL), respectively. IgH/Bcl6 fusion was seen in 2 case of DLBCL and IgH/C-myc fusion was seen in 1 case of Burkitt lymphoma (BL). Finally, our cohort included 82 B-cell lymphomas (91%) and 8 T-cell lymphomas (9%). Subclassification of lymphoma in accordance with WHO system included 40 cases of FL, 39 cases of DLBCL, one case of BL, 2 cases of lymphoblastic lymphoma, 7 cases of peripheral T cell lymphoma not specified, and one case of angioimmunoblastic lymphoma. Although all of the outpatients were hospitalized until the day after biopsy, there were no serious complications related to this procedure like bleeding, perforation, ileus, and infection.

Conclusions: EUS-FNAB using a standard 19 or 22-gauge needle is safe and feasible and has high diagnostic value for subclassification of intra-abdominal lymphoma without accessible peripheral lymphadenopathy. With the use of simultaneous immunophenotyping, molecular, and cytogenetic studies, lymphoma subclassification was possible in most of the cases.