Endocrine Abstracts

Background: Fine needle aspiration (FNA) is the diagnostic procedure of choice in the evaluation of thyroid nodules. Nodules with indeterminate cytological categories, Tir3A and Tir3B according to Italian cytological classification, pose diagnostic challenges in clinical practice and are frequently submitted to diagnostic surgery. CytoFoam Core (CF) (Diapath, Martinengo, Italy) uses an absorbent foam device inserted into the needle hub to collect the cytological sample aspirated during FNA. The specimen is formalin-fixed and paraffin-embedded similarly to the microhistological material obtained with core-needle biopsy.

Aim of the study: To assess diagnostic efficacy of CytoFoam core, compared to traditional cytology, in re-evaluating thyroid nodules classified as Tir3A. Post-surgical histology was used as reference standard.

Method: Retrospective study on 89 patients with a first indeterminate cytological report who were referred to the 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. During the second procedure, both traditional cytological (TC) smears and a single-pass CF specimen were obtained for each patient. On CF samples immunocytochemical staining for Galectin-3, HBME-1, and CK-19 was also performed. Forty-five patients eventually underwent surgery, and their histological diagnoses were compared to the TC and CF reports. Four parameters were blindly and independently compared by two cytopathologists with specific thyroid expertise: inadequacy rate, rate of persistent indeterminate (Tir3A and Tir3B) reports, rate of malignancy in persistently indeterminate nodules, and rate of cancer in lesions cytologically classified as malignant.

Results: Non-diagnostic samples were 8/45 (17.7%) in TC vs 5/45 (11.1%) in CF samples (P=0.4). Persistent indeterminate samples were 27/45 (60%) in TC vs 16/45 (35.5%) in CF samples (P<0.005). The rate of malignancy in persistently indeterminate nodules was 8/16 (50%) in CF group vs 9/27 (33.3%) in TC group (P=0.4). Five/45 (11.0%) samples were classified as benign by TC vs 16/45 (35.0%) samples by CF (P<0.005). All these nodules resulted benign at post-surgical evaluation. Five/45 (11.0%) samples were classified as suspicious for malignancy/malignant in TC group against 8/45 (18.0%) samples in CF (P=0.4). Post-surgical evaluation confirmed malignancy in all these cases.

Conclsion: CytoFoam core demonstrated greater diagnostic accuracy than TC in repeat FNA assessment of cytologically indeterminate nodules. CF increased the conclusive diagnosis rate and decreased the number of cytologically indeterminate cases. A large prospective study is needed to confirm this pilot study results.