Cell block specimens applied to diagnostic routine of thyroid fine-needle aspiration biopsy

ABSTRACT Introduction: Various preparations can be used in diagnostic cytology, including conventional smears (CS), liquid-based preparations (LBP) and cell block (CB). Objective: The aim of this study is to evaluate the quality of CB preparations in addition to conventional cytological specimens in cases of fine-needle aspiration biopsy (FNAB) of thyroid nodules in diagnostic routine. Method: One hundred and six consecutive cases of FNAB routine thyroid nodules were independently evaluated by two cytopathologists (Obs1 and Obs2) on the cellularity of SM, LBP and CB. Results: The cellularity was rich/moderate in 56 (52.8%) CBs for both observers. LBP showed rich/moderate cellularity in 86 (81.1%) cases for Obs1 and 91 (85.8%) for Obs2; among these cases, CB showed the same cellularity in 52/86 (60.4%) cases for Obs1 and 54/91 (59.3%) for Obs2. SM showed rich/moderate cellularity in 86 (81.1%) cases for Obs1 and 87 (82%) for Obs2; among these cases, CB showed the same cellularity in 48/86 (55.8%) cases for Obs1 and 54/87 (62%) for Obs2. CB cellularity was higher than that in LBP in only five cases for Obs1 and three for Obs2. LBP was assessed as low/absent in only five (4.7%) and six (5.6%) cases for Obs1 and Obs2, respectively. Conclusion: CB can be routinely used as additional specimen in material obtained from thyroid nodules FNAB, without adversely affecting LBP specimens, enabling the conduction of further immunohistochemical and molecular studies.