20.500.12556/RUL-184919 Cellularity of routinely prepared cell blocks insights from an international study Objective: Formalin-fixed, paraffin-embedded (FFPE) cell blocks (CBs) are widely used for processing cytology specimens, but preparation methods remain variable and non-standardised. Low cellularity is a common limitation that may compromise diagnostic utility. This study aimed to evaluate the cellularity of routinely prepared CBs across different preparation methods, laboratories and sample types. Methods: Each laboratory in this multicentre observational study retrospectively assessed 50 consecutive CBs prepared using a single method. Cellularity of Haematoxylin and Eosin (H&E)-stained sections was semi-quantitatively evaluated by two independent reviewers per laboratory in four categories: acellular, low (≤ 100 cells), medium (100-500 cells) and high cellular (> 500 cells). The proportion of poorly cellular CBs (acellular + low cellular) was compared across methods, laboratories and sample types using non-parametric tests. Results: Cellularity was assessed for 1817 CBs prepared using Agar (22%), HistoGel (19%), Plasma-Thrombin (19%), Cellient (17%), In-house (15%) and Shandon/Epredia (8%) methods. The proportion of poorly cellular CBs ranged from 4% to 80% across laboratories (mean 27%, median 25%), with no consistent clustering by method. Median proportions by method ranged from 12% (Cellient) to 35% (Agar), but inter-method differences were not statistically significant (p > 0.05). Substantial variability was observed both across and within sample types and preparation methods. Conclusions: The study revealed marked variability in the proportion of poorly cellular CBs among preparation methods and laboratories, highlighting the need for improved processing and monitoring of CB adequacy. cell block cellularity cytology preparation of method celični blok celularnost citologija metoda priprave true false true Angleški jezik Slovenski jezik Članek v reviji 2026-07-17 08:15:48 2026-07-17 08:16:03 2026-08-11 07:39:46 0000-00-00 00:00:00 2026 0 0 Str. 214-221 iss. 3 Vol. 37 2026 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 616:576 0956-5507 10.1111/cyt.70065 271666691 RAZ_Srebotnik-Kirbis_Irena_2026.pdf RAZ_Srebotnik-Kirbis_Irena_2026.pdf 1 2AB24327DA5552370C2192DD39B38C9F db5daeea87665d03d541a769a44859c50e242b331332f5fd561b60457196333f 52aa8fd7-81a7-11f1-9b0d-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=240321 https://onlinelibrary.wiley.com/doi/10.1111/cyt.70065 1 cc612de6-81a6-11f1-9b0d-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=240320 Medicinska fakulteta 0 0 0