Diagnostic significance of GATA 3, TTF‐1, PTH, chromogranin expressions in parathyroid fine needle aspirations via immuonocytochemical method

Background Additional studies may be needed when evaluating parathyroid fine needle aspirates (FNA) due to cytomorphologic similarities. The liquid‐based cytology (LBC) is an effective cytology method which provides additional slides for ancillary techniques. We aimed to examine the immunocytochemical (ICC) GATA 3, TTF‐1, which chromogranin and PTH expressions and to determine their diagnostic importance in parathyroid FNAs which were prepared via LBC technique. Methods In total, 45 parathyroid FNA cases were examined in our laboratory for 12‐month period. Thirty five cases without cell blocks were included in the study. Ten cases were excluded from study (five cases were nondiagnostic, five cases had cell blocks). For main LBC cytology slides SurePath pap test kit was used. For ICC study 4 PAP‐stained LBC slides were obtained from each case's residual material. The slides were then stained with GATA 3, TTF‐1, PTH and chromogranin. Results Of 35 cases, 8 were male and 27 were female. The mean age of the cases was 52.25 ± 11.44 (range 27–72). The mean diameter of the lesions was 18.54 ± 7.66 mm (range 6–32 mm).The most used antibody was TTF‐1 (in all 35 cases). The positivity rates were 84.8%, 83.9% and 81.8% for GATA 3, PTH and chromogranin, respectively. TTF‐1 was completely negative in 100% of cases. All patients had high PTH washout values (29 patients, PTH washout value was >5000 pg/mL). In 30 cases, histopathologic follow‐up was available. The cyto‐histological correlation was 100%. Based on the PTH washout values for cases without resection, the diagnostic accuracy of FNA was determined as 100% in detecting the parathyroid origin. Among the antibodies, the most specific and sensitive antibody was TTF‐1 (100%). The sensitivity values of the antibodies indicating parathyroid origin for GATA3, PTH and chromogranin were 86.67%, 83.33% and 81.82%, respectively. Conclusion The addition of ICC studies applied to LBC slides is also very helpful in diagnosis, especially in FNAs with limited material such as parathyroid. GATA3 is a more reliable ICC marker determining parathyroid origin. In differentiation from thyroid origin, the addition of TTF‐1 to the ICC panel increases the diagnostic accuracy to 96.67%. Although PTH and chromogranin have lower sensitivity, they are still reliable markers to detect parathyroid origin.