The use, publication and future directions of immunocytochemistry in veterinary medicine: a consensus of the Oncology‐Pathology Working Group

Abstract

One of the primary objectives of the Oncology Pathology Working Group (OPWG), a joint initiative of the Veterinary Cancer Society and the American College of Veterinary Pathologists, is for oncologists and pathologists to collaboratively generate consensus documents to standardize aspects of and provide guidelines for oncologic pathology. Consensus is established through review of relevant peer-reviewed literature relative to a subgroup's particular focus. In this document, the authors provide descriptions of the literature reviewed, the review process, and a summary of the information gathered on immunocytochemistry. The intent of this publication is to help educate practitioners and pathologists on the process of immunocytochemistry and to provide a guide for the use of this technique in veterinary medicine. This document represents the opinions of the working group and the authors and does not constitute a formal endorsement by the American College of Veterinary Pathologists or the Veterinary Cancer Society.

The cell tube block technique and an immunohistochemistry panel including Wilms tumor 1 to assist in diagnosing cavitary effusions in dogs and cats

“…In this respect, vimentin should be associated with other mesothelial markers; however, the well‐recognized markers used in human mesothelial tissues, such as calretinin and HBME‐1, have shown inconsistent or negative results in animals . Desmin immunostaining has been recently proposed, but this marker seems less reliable in the veterinary field than in human medicine, with mesothelial cell cytoplasm appearing variably stained . Moreover, despite the fainter desmin immunostaining, it has been expressed in carcinomatous effusions .…”

“…Immunostains that can distinguish between mesothelial, both reactive or neoplastic, and epithelial cells in effusions continue to be evaluated in human pathology . Such a comprehensive evaluation has never been performed in the veterinary field, although its importance is well recognized . In fact, only a handful of reports have evaluated the use of IHC and CB in small animals, and vimentin has been used as a sole marker for mesothelial cells .…”

“…However, this could raise problems since vimentin‐positive neoplastic cells other than mesothelial cells can appear in effusions, as in the case of other mesenchymal tumors, such as osteosarcomas . The use of more than one marker or panel of antibodies for mesothelial cells has been long proposed in human pathology, while in veterinary medicine, a few markers, such as calretinin, Hector Battifora Mesothelial cell‐1 (HBME‐1), and desmin have been studied with mediocre results …”

Veterinary Pathology – A Path Forward with New Directions and Opportunities

“…Nevertheless, many laboratories voluntarily participate in external proficiency testing, with recommendations for this testing being established by the American Society of Veterinary Clinical Pathology (23). Guidelines and consensus statements have been generated for several diagnostic activities, including reference interval establishment (24), prognostic markers in cancer (25), flow cytometric reporting in canine hematopoietic neoplasia (26), immunocytochemical staining (27), and viscoelastic-based hemostasis testing (28), to name a few examples. Similarly, cytologic (29) and histologic (30, 31) grading schemes have been proposed for various tumors.…”

Validation of an immunocytochemical assay for immunophenotyping of lymphoma in guinea pigs (Cavia porcellus)

“…This study sought to accomplish both of these objectives, and develop an immunocytochemical (ICC) assay to better characterize lymphoproliferative neoplasia through T‐ and B‐cell phenotyping in guinea pig patients. Several groups have recently emphasized proper validation of antibodies for use in ICC, including the American Society of Veterinary Clinical Pathology (ASVCP) Quality Assurance Guidelines (https://cdn.ymaws.com/www.asvcp.org/resource/resmgr/qals/qals_icc_guidelines_11.2017.pdf) and the Oncology‐Pathology working group . A recent review suggests that validation of an antibody for immunohistochemical use in a new species should include both Western blotting to demonstrate reactivity with the appropriate molecular weight antigen as well as tissue distribution studies in formalin‐fixed, paraffin‐embedded tissues…”