Endocrine Abstracts

Background: Fine needle aspiration (FNA) is the procedure of choice in the evaluation of thyroid nodules. Nodules with indeterminate cytological categories, Bethesda III and IV, pose challenges in clinical practice and are frequently submitted to diagnostic surgery. Immunohistochemistry provides complementary information to cytological findings but its reliable use on FNA samples is hampered by technical problems. CytoFoam Core (CFCS), an absorbent foam device inserted into the needle hub, collects the cytological sample aspirated during FNA and may overcome these difficulties because a formalin-fixed and paraffin-embedded specimen, well suitable for ancillary techniques, is provided.

Aim of the study: To assess diagnostic efficacy of CFCS, compared to traditional cytology, in re-evaluating thyroid nodules classified as Bethesda III. Post-surgical histology was used as reference standard.

Method: Retrospective study on 89 patients with a first indeterminate cytological report referred to Department of Endocrinology of Regina Apostolorum Hospital (Albano L. Rome, Italy) for a second FNA. FNA was performed, after at least one month, under ultrasound guidance with a 23G needle according to the established procedure. Both traditional cytological (TC) smears and a single-pass CFCS specimen were obtained for each patient. On CFCS samples immunocytochemical staining for Galectin-3, HBME-1, and CK-19 were performed. Fifty-one patients underwent surgery and their histological diagnoses were blindly compared to the TC and CFCS reports. Four parameters were evaluated: inadequacy rate, rate of persistent indeterminate (Bethesda III and IV) reports, rate of malignancy in persistently indeterminate nodules, and rate of cancer in lesions cytologically classified as malignant.

Results: Non-diagnostic samples were 6 (11.8%) in TC vs 3 (5.9%) in CFCS (P=0.4). Persistent indeterminate samples were 31 (60.8%) in TC vs 19 (37.2%) in CFCS (P=0.01). Rate of malignancy in persistently indeterminate nodules was 8/19 (42.1%) in CFCS vs 9/31 (29%) in TC group (P=0.3). Nine/51 (17.6%) samples were reclassified as benign by TC vs 21/51 (41.2%) samples by CFCS (P<0.01). All benign nodules were confirmed as benign at post-surgical evaluation. Five/51 (9.8%) samples were classified as suspicious for malignancy/malignant in TC group against 8/51 (15.7%) samples in CFCS (P=0.5). Post-surgical evaluation confirmed malignancy in all these cases.

Conclusion: CFCS significantly improved diagnostic accuracy of TC in repeat FNA assessment of cytologically indeterminate nodules. CFCS increased the conclusive diagnosis rate and decreased the number of cytologically indeterminate cases.