Three cell block preparation methods converging into a diagnostic point represented by a microscope lens focusing on granulomas.

Cell Block Showdown: Which Method Gives You the Most Bang for Your Biopsy?

Lena Voss in Health & Wellness December 2025 • 4 min read.

"Comparing plasma-thrombin, HistoGel, and CellGel for diagnosing mediastinal granulomatous disease."

In the realm of pathology, cell block (CB) preparation methods are essential for diagnostic accuracy. Laboratories often use varied CB techniques, sometimes alongside ThinPreps (TPs). This article delves into a comparative analysis of different CB methods, evaluating their effectiveness and diagnostic value when used with TP. The focus is on the quantity and size of granulomas obtained from endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) of lymph nodes, specifically in diagnosing granulomatous mediastinal disease.

The study retrospectively examines mediastinal lymph node EBUS-TBNA specimens from an institution. A total of 264 specimens from 124 patients were analyzed, each having a TP followed by a CB prepared from the residual material in the PreservCyt vial. The key parameters assessed were the number and size of granulomas on each preparation, measured using digital software to ensure precision and consistency.

The results indicated that granulomas were detected only on the CB in 18.9% of cases and only on the TP in 5.3%. Each CB preparation method showed significantly more and larger granulomas compared with the paired TP. Plasma-thrombin and CellGel methods yielded more diagnostic material than the HistoGel method. The average number of granulomas (4.0 ± 0.4 versus 15.3 ± 1.1) and granuloma size (119.2 ± 3.2 µm versus 271.8 ± 7.3 µm) were significantly lower on TP compared with CB, respectively.

Unpacking Cell Block Methods: Plasma-Thrombin, HistoGel, and CellGel

Three cell block preparation methods converging into a diagnostic point represented by a microscope lens focusing on granulomas.

Cell block preparation methods serve as vital tools in pathology, offering a concentrated sample of cells for analysis. Let's examine the primary techniques evaluated in the study:

Plasma-Thrombin: This method involves clotting the cellular pellet with expired blood bank plasma and saline-reconstituted thrombin. The resulting clot is then processed as a routine formalin-fixed, paraffin-embedded histological sample.

Simple to perform using readily available materials.
Quick clot formation time.
Potential variability in clot formation and cell concentration.

HistoGel: This technique uses a specialized gelatinous substance (HistoGel) to embed the cell pellet. After centrifuging the sample, warmed HistoGel solution is added to the pellet, allowed to cool and congeal, and then processed like a standard histological sample. Key considerations include:

Good cellular and architectural preservation.
Potential difficulties in extracting all material from the conical tube.
Possibility of uneven cell distribution on histologic sections.

Key Takeaways

In summary, the choice of cell block preparation method can significantly impact diagnostic yield. Plasma-thrombin and CellGel methods outperformed HistoGel in this study, providing more diagnostic material and larger granulomas. Always ensure concurrent CB preparations are performed, as relying solely on TP slides may lead to missed diagnoses in a notable percentage of cases.

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Everything You Need To Know

What is the role of cell block preparation in diagnosing mediastinal granulomatous disease?

Cell block (CB) preparation methods are crucial for accurate diagnoses in pathology, particularly when dealing with mediastinal granulomatous disease. These methods concentrate cellular material, which is essential for detecting and analyzing granulomas. By comparing different CB methods alongside ThinPreps (TPs), the effectiveness of each method in identifying and characterizing granulomas from endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) specimens can be evaluated. This ensures that the diagnostic yield is maximized, and the most accurate results are obtained for patient care.

How do the Plasma-Thrombin, HistoGel, and CellGel methods differ in cell block preparation?

The Plasma-Thrombin method uses expired blood bank plasma and saline-reconstituted thrombin to clot the cellular pellet. This forms a clot that is processed like a standard histological sample. HistoGel involves embedding the cell pellet in a specialized gelatinous substance. After centrifugation, warmed HistoGel is added, allowed to cool and congeal, and then processed. CellGel, like Plasma-Thrombin, also aims to consolidate the cellular material for easier processing and analysis. The choice of method impacts factors like clot formation speed, cellular preservation, and the ease of extracting the material, which subsequently affects diagnostic outcomes.

What were the key findings when comparing cell block methods with ThinPreps (TPs) in the diagnosis of mediastinal granulomatous disease?

The study revealed that cell block (CB) preparations consistently outperformed ThinPreps (TPs) in detecting granulomas from endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) specimens. Granulomas were detected more frequently and were larger in CB preparations compared to TPs. Specifically, the average number of granulomas and granuloma size were significantly lower on TPs. Furthermore, Plasma-Thrombin and CellGel methods generally yielded more diagnostic material than the HistoGel method. These findings underscore the importance of CB methods for improving diagnostic accuracy.

Why is it important to perform concurrent cell block (CB) preparations alongside ThinPrep (TP) slides?

Performing concurrent cell block (CB) preparations alongside ThinPrep (TP) slides is critical because CB methods can detect granulomas that might be missed when relying solely on TPs. The study indicated that granulomas were detected only on the CB in a notable percentage of cases, highlighting that TPs alone can lead to missed diagnoses. Utilizing both methods increases the likelihood of accurate diagnoses, particularly in cases of mediastinal granulomatous disease, where identifying and characterizing granulomas is key to effective patient management.

What are the practical implications of using Plasma-Thrombin, HistoGel, and CellGel methods in a laboratory setting, and what factors should guide the selection of one over the others?

In a laboratory setting, each cell block (CB) preparation method presents practical considerations. Plasma-Thrombin is simple and uses readily available materials, but it may have variability in clot formation. HistoGel offers good cellular preservation but can be difficult to extract all material from the conical tube, potentially leading to uneven cell distribution. CellGel, like Plasma-Thrombin, also aims to consolidate the cellular material. The choice between these methods should be guided by factors such as the desired speed, available resources, and the importance of optimal cell preservation. Based on the study findings, Plasma-Thrombin and CellGel methods showed a better diagnostic yield compared to HistoGel. Laboratories should assess these factors, as well as consider the specific clinical context and diagnostic goals, to select the most appropriate CB preparation technique for the best patient outcomes.