Fine-Needle Aspiration Biopsy as a Diagnostic Modality for Orbital Adnexal Lymphoma.

Introduction: The aim of this study was to evaluate fine-needle aspiration biopsy (FNAB) as a diagnostic tool for lymphoproliferative orbital lesions in light of recent improvements in cytomorphological and immunologic analyses.

Method: Retrospective case series including all orbital FNABs with a lymphoproliferative outcome at Karolinska University Hospital, Stockholm, Sweden during the period 2005-2015.

Results: Of the 38 patients included, 31 (82%) were conclusively diagnosed as having lymphoma according to the first FNAB. Disease in 20 patients (65%) could be subclassified. The diagnosis in 7 patients (18%) was either inconclusive, suggestive of lymphoma, or reactive lymphatic infiltrate. These 7 patients were re-investigated, and the initial suspected diagnosis of malignant lymphoma was confirmed in four. Two of the remaining 3 patients were initially diagnosed as having non-lymphoproliferative disease; however, this was later changed to a lymphoproliferative diagnosis following reinvestigation, while the results of both reFNAB and incisional biopsy were inconclusive in the third.

Conclusion: In the majority of the 38 patients, a definitive diagnosis of lymphoma could be made based on FNAB alone, using cytomorphological and immunological workup, and subclassification was possible in 20 patients (65%). Primary low-grade malignant orbital lymphomas are traditionally treated with low-dose radiotherapy regardless of subtype, and incisional biopsy was not needed to initiate treatment. Our findings suggest that FNAB is a valid first option for the diagnosis of suspected orbital lymphomas due to the minimal risk of complications compared to incisional biopsy, and the fact that it can be performed as an outpatient procedure with no anesthesia.