Follow-up of morphologically reactive lymphoid proliferations in fine-needle aspirates of elderly patients

Fine-needle aspiration (FNA) is an effective tool in evaluating the cause of lymphadenopathy. While the morphologic diagnosis of a reactive lymphoid proliferation is common in younger patients, this diagnosis should be made carefully in older patients (those over the age of 50 yr) in light of the facts that such purely reactive conditions occur much less frequently in this population, and that follow-up of these patients reveals a malignancy (usually lymphoma) in a significant number of cases. In this series, we identified 40 patients with a morphologic diagnosis of reactive lymphoid proliferation on FNA and obtained their follow-up information. Of 19 patients under the age of 50 yr, 5 underwent subsequent biopsies and only one revealed a definitive malignancy (5%). In contrast, 7 of 21 patients over the age of 50 yr underwent a subsequent biopsy, and 6 were found to have a malignancy (5 malignant lymphomas, 1 metastatic melanoma). The higher rate of positive follow-up (29%) in this age group supports previous suggestions that morphologically reactive (mixed) lymphoid proliferations be viewed with increased suspicion in the elderly patient, and that additional studies, such as flow cytometry, be performed when material is available.