Cell blocks in veterinary medicine: A comparison of two methods (cell tube and agar) in 52 effusions from dogs and cats

Abstract

BackgroundCell blocks are alternative preparations of fluid cytological specimens. They can be used for immunochemical studies as complementary tools or when other techniques (eg, immunocytochemistry, flow cytometry) are not available.ObjectivesWe aimed to provide comparative morphologic, immunohistochemical, and technical features of agar‐based cell blocks (ACBs) and cell tube blocks (CTBs) from cavitary effusions.MethodsAgar‐based cell blocks and CTBs were obtained from canine and feline effusions with neoplastic/atypical cells or with packed cell volumes ≥3%. Cellularity, RBC separation, and cellular features were evaluated on digitalized H&E slides with evaluators blinded to the method. The immunohistochemical intensity and nonspecific background were assessed on pan‐cytokeratin and vimentin‐stained slides. Overall yield was calculated, and morphologic and immunohistochemical features were compared among paired samples. Technical and cellular features were also described.ResultsAgar‐based cell blocks and CTBs yielded evaluable sections in 100% (52/52) and 98% (51/52) of the cases, respectively. Cellularity and RBC separation scores were significantly higher in CTBs. Similar staining intensities were observed, and background staining was more frequently seen in pan‐cytokeratin‐stained ACBs. Only basic materials and equipment were required for both methods. Agar‐based cell block preparations were more operator dependent and difficult to standardize, whereas CTBs were easier to prepare, but laboratory processing was more demanding.ConclusionsBoth methods can be used to produce good sections for immunohistochemistry staining with no significant differences. Cell tube blocks are beneficial for RBC‐rich samples, and little additional training is required to prepare the blocks. Both types of cell blocks are reliable, cost‐effective methods that could be introduced in diagnostic laboratories to further characterize canine and feline effusions.

Multiple myeloma in dogs: Use of the cell block technique as a new diagnostic tool

“…Cell blocks have stood out in the diagnosis of neoplastic processes, obtaining good results mainly from the characterization and immunophenotyping of the cells involved 7,9–12,20 . When performed from organ and tissue aspirates, the cell block technique is considered an excellent alternative to cytologic immunostaining when incisional biopsies are not possible due to the fact that the comparison between antibody staining is very precise since the same cells are being evaluated, regardless of the number of antibodies used 21 .…”

“…Cell blocks have stood out in the diagnosis of neoplastic processes, obtaining good results mainly from the characterization and immunophenotyping of the cells involved. 7,[9][10][11][12]20 When performed from organ and tissue aspirates, the cell block technique is considered an excellent alternative to cytologic immunostaining when incisional biopsies are not possible due to the fact that the comparison between antibody staining is very precise since the same cells are being evaluated, regardless of the number of antibodies used. 21 Although fine needle aspiration cytologic examination is a quick procedure, a low-cost tool with high sensitivity and specificity in the diagnosis of lymphoproliferative processes, it has its limitations, and other techniques are being applied to improve its diagnosis.…”

“…7 The cell block technique, which has been used for decades in human medicine, 8 was recently adopted as a technique in veterinary medicine and applied to the diagnosis of cavitary effusions and neoplastic and infectious processes. 7,[9][10][11][12] Several techniques can be used to make these blocks, all involving two distinct phases-the preparation, where there are variations, and the processing, which is similar in all methods. 7 Although they can be used with various biological specimens, cell blocks have been more frequently recommended for cytologic samples that are concentrated and embedded in paraffin.…”

“…7,[9][10][11][12] Several techniques can be used to make these blocks, all involving two distinct phases-the preparation, where there are variations, and the processing, which is similar in all methods. 7 Although they can be used with various biological specimens, cell blocks have been more frequently recommended for cytologic samples that are concentrated and embedded in paraffin. 8 One study validated the usefulness of HistoGel cell blocks in routine veterinary diagnostic cytology and confirmed that immunohistochemistry can be performed on HistoGel-embedded cytologic samples without any interference using standardized methods developed for histopathology.…”

Needle rinse cell blocks as an ancillary technique: Diagnostic and clinical utility in gastrointestinal neoplasia

“…Since fixation is achieved at the top of the cell tube, it might be suboptimal when excessive material is present in the capillary (Figure 1). 19 …”