Cell Block in Cytological Diagnostics: Review of Preparatory Techniques

Abstract

Objective: The cell block (CB) technique refers to the processing of sediments, blood clots, or grossly visible tissue fragments from cytological specimens into paraffin blocks that can be cut and stained by the same methods used for histopathology. The technique brings additional tissue architectural information. CB can be used for ancillary techniques such as immunocytochemistry and molecular techniques. Study Design: We reviewed the literature on the various preparatory techniques of CBs. Results: There is a wide range of preparatory techniques for CBs and no golden standard for CBs exists: tens of methods are used in various institutions. The majority of the methods are modified in house techniques with a few commercially available kits. The techniques most commonly used are the plasma/thrombin method, the agar method, and commercially available Histogel- and Cellient CB-methods. Dissatisfaction with the cellular yield of the CBs is common. Conclusions: In the CBs, the cytological material is preserved for future use, which is a tremendous advantage in the era of targeted therapy and biobanking. The CB is thus central to the future of cytology: more can be done with less material and with less invasiveness to the patient.

New Cell Block Method to Enhance the Cellular Yield in Mucous and/or Bloody Samples

“…There is a tendency to use less invasive procedures at outpatient clinics for diagnostics, and for this purpose the collection of cytological material suits better than the more invasive surgical methods. In this light, the CB is central to the future of cytology: we can do more with less [3,14]. Nevertheless, the low satisfaction with CBs due to low cellularity was shown in the recent survey [15] and during numerous personal communications at cytology meetings.…”

“…Disadvantage of thin concentrated layer of cells was shown with some other techniques, where only a limited number of cellular sections is achieved. The idea of cell concentration by red blood cell lysis was introduced by several authors [9][10][11][12][13], it is widely used, and the majority of used lysates do not interfere with the morphology of cells [3,16].…”

“…Nevertheless, cytological material is not always available for CB preparation and the cellularity of the CB can be unsatisfactory due to preanalytic variables namely type, nature, and location of lesion as well as the skills and technique of the operator obtaining the specimen. To reduce the unsatisfactory samples, it is necessary to have different cytological techniques available [3,18].…”

“…The majority of the studies on CBs are made on limited types of material (either effusions or FNAs) not rep-resenting the whole spectrum of cytology; and furthermore, the numbers of studied cases is limited (around ten) [3]. In the presented study, all consecutive routine cytological samples were triaged and mucous and/or bloody samples were used to develop and successfully test the in-house method.…”

“…Cell blocks (CBs) can be prepared by a wide variety of techniques [1][2][3]. The main principle in each technique is the concentration of cells and processing into paraffin blocks.…”