Evaluation of HistoGel™-embedded specimens for use in veterinary diagnostic pathology

Joiner, Kellye S.; Spangler, Elizabeth

doi:10.1177/1040638712445763

Cited by 23 publications

(25 citation statements)

References 3 publications

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“…After resuspension in HistoGel (RichardAllan Scientific, Kalamazoo, MI), such cell pellets can then be fixed in 10% NBF and routinely processed for histopathology, IHC, and ISH like any other tissue sample. 53 …”

Section: In Situ Hybridizationmentioning

confidence: 99%

Beyond H&E

et al. 2013

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Veterinary pathology of infectious, particularly viral, and neoplastic diseases has advanced significantly with the advent of newer molecular methodologies that can detect nucleic acid of infectious agents within microscopic lesions, differentiate neoplastic from nonneoplastic cells, or determine the suitability of a targeted therapy by detecting specific mutations in certain cancers. Polymerase chain reaction-based amplification of DNA or RNA and in situ hybridization are currently the most commonly used methods for nucleic acid detection. In contrast, the main methodology used for protein detection within microscopic lesions is immunohistochemistry. Other methods that allow for analysis of nucleic acids within a particular cell type or individual cells, such as laser capture microdissection, are also available in some laboratories. This review gives an overview of the factors that influence the accurate analysis of nucleic acids in formalin-fixed tissues, as well as of different approaches to detect such targets. Keywords cancer, ISH, IHC, nucleic acid analysis, molecular pathology, PCR, virology Technical ConsiderationsTissue Handling, Fixation, and Embedding Fixation of tissues in 10% neutral buffered formalin, followed by paraffin embedding (FFPE), has long been the standard approach of tissue preparation for microscopic evaluation. The chemical principle of formalin fixation is based on the crosslinking of proteins. Formalin has been used extensively because it is inexpensive and excellently preserves morphological detail in histological sections. However, the relatively recent development and increasing use of both protein and nucleic acid detection methods have revealed some significant shortcomings associated with the formalin-based fixation process. The effects of formalin fixation on DNA are chemical modification, DNA trapping, and potentially DNA fragmentation. Chemical modification, considered the main effect, results from the direct cross-linking of proteins to DNA. 68 In addition, extensive protein-protein cross-linking and the formation of protein networks result in DNA trapping. The combination of these effects makes it much more difficult to extract DNA from FFPE tissue than from unfixed tissue, especially when methods used for extraction from fresh tissues are used on FFPE tissue without any modifications. 60,83 In addition to interfering with the ability to extract nucleic acid, formalin fixation also causes DNA fragmentation, especially when the formalin used is inadequately buffered, which then leads to formic acid formation during the fixation process. This, in turn, results in depurination of the DNA, which then becomes susceptible to cleavage by hydroxyl ions and results in the formation of single-stranded breaks.60 Similar to DNA, RNA is also degraded and chemically modified as the result of formalin fixation. The most important chemical effect of formalin on RNA is the formation of monomethylol groups with purine bases. 77 This has a significant effect on reverse transcription ...

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Section: In Situ Hybridizationmentioning

confidence: 99%

Beyond H&E

et al. 2013

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“…Histogel preparations were made as previously described . Briefly, the solidified Histogel (Richard‐Allan Scientific, Kalamazoo, MI, USA) was melted by placing the tube of Histogel in a water bath and heating to 55‐65°C.…”

Section: Methodsmentioning

confidence: 99%

“…Cell block preparation techniques that can be performed by veterinarians in‐house could be useful in limiting the effects of storage and temperature on cell morphology and could also limit the need for a cytocentrifuge. Histogel is an aqueous gel that allows suspension of tissue and fluid samples in a solidified medium . These specimens are then formalin‐fixed, processed, and evaluated by routine histologic and immunohistochemical methods.…”

Section: Introductionmentioning

confidence: 99%

“…Cell block preparations could minimize the effects of cell lysis and degradation associated with delayed sample processing by immediately suspending cytologic samples into a gel or foam matrix, followed by formalin fixation. A further advantage of using Histogel and Gelfoam preparations is the potential for immunohistochemical staining, which could facilitate the evaluation of different inflammatory cell types or neoplastic cells. Only standard centrifugation is needed to prepare cell suspensions for sediment smears and cell block techniques, thereby removing the need for special equipment such as a cytocentrifuge.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Histogel‐ and Gelfoam‐embedded bronchoalveolar lavage and transtracheal wash fluids compared with cytocentrifuged and sediment smear preparations

Haysom

Lee‐Fowler

Spangler

2018

Veterinary Clinical Pathol

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TNCCs impacted the cellularity of the sediment smears and Histogel preparations. Cytocentrifuged preparations resulted in the best cellularity and morphology and are, therefore, recommended whenever possible. Neither the Histogel nor the Gelfoam methods demonstrated any advantage over sediment smear preparations, and both performed poorly when compared with cytocentrifuged preparations. Therefore, we do not recommend the use of these methods.

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“…Proposed advantages of the CB as documented in human studies include: (a) the preservation of tissue architecture, (b) sample archivability owing to paraffin embedding, (c) the suitability of samples for cytochemical and immunohistochemical staining, (d) a reduced need for excisional biopsy and (e) advantages in the detection of certain malignancies, including lymphoma . Limited studies on the CB or CB‐like techniques in veterinary medicine have demonstrated its utility in the evaluation of lymphoid tissues and in the detection of fungal osteomyelitis, leishmaniasis, mesothelioma and bone marrow carcinoma micrometastasis . While all veterinary publications describing the CB testify to its ease of use, only one has evaluated its utility in the evaluation of the canine reactive and lymphomatous lymph node and in the diagnosis of lymphoma.…”

Section: Introductionmentioning

confidence: 99%

Cytology and the cell block method in diagnostic characterization of canine lymphadenopathy and in the immunophenotyping of nodal lymphoma

Heinrich

Avery

Henson

et al. 2019

Vet Comparative Oncology

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Minimally invasive techniques used to evaluate canine peripheral lymphadenopathy (PLN), including fine needle aspiration biopsy with cytological evaluation (FNAB‐C) and flow cytometry (FC), have benefits and limitations. The cell block (CB) method is an alternate processing technique in which fine needle aspirate biopsy samples are concentrated, fixed, and embedded in paraffin for routine histological processing/staining. Utilizing three observers, we determined the diagnostic value of the CB in evaluating canine PLN across six categories (non‐diagnostic, reactive, inflammatory/infectious, probable lymphoma and lymphoma, metastatic neoplasia) and correlated findings to immunophenotypic and clonal antigen receptor rearrangement results in canine nodal lymphoma. Eighty‐five paired FNAB‐C and CB samples were evaluated from canine patients presenting to the University of Minnesota Veterinary Oncology or Internal Medicine services. Diagnostic quality samples were obtained in 55/85 (65%) CB and 81/85 (95%) FNAB‐C samples, respectively, and nodal pathology impacted CB diagnostic yield. Overall percent agreement between diagnostic‐quality FNAB‐C and CB samples was 86%, but increased to 95% if the categories of lymphoma and probable lymphoma were combined. There was 100% agreement for both the diagnoses of metastatic neoplasia and reactive lymph nodes and 92% agreement for the diagnosis of lymphoma/probable lymphoma. Using immunohistochemistry (IHC), CB samples correctly immunophenotyped 22/23 (96%) cases of B‐cell lymphoma, but only 1/6 (17%) cases of T‐cell lymphoma. IHC was not completed on nine cases of lymphoproliferative disease because of insufficient cellularity. When the CB method (CBM) yielded diagnostic quality samples there was good to excellent agreement with FNAB‐C samples and CB samples were suitable for some IHC tests.

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Evaluation of HistoGel™-embedded specimens for use in veterinary diagnostic pathology

Cited by 23 publications

References 3 publications

Beyond H&E

Beyond H&E

Evaluation of Histogel‐ and Gelfoam‐embedded bronchoalveolar lavage and transtracheal wash fluids compared with cytocentrifuged and sediment smear preparations

Cytology and the cell block method in diagnostic characterization of canine lymphadenopathy and in the immunophenotyping of nodal lymphoma

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