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

Abstract

Background: Cell blocks and immunohistochemistry (IHC) are increasingly recognized as being complementary tools for cytologic diagnostics, especially for neoplastic diseases. Objectives:The study aimed to evaluate the utility of cell tube block (CTB) IHC for refining the diagnosis of effusions in dogs and cats.Methods: Cavitary effusions (n = 25) from dogs and cats classified by cytology as reactive, neoplastic, borderline (suspicious of neoplasia), and chylous were studied.CTB sections were stained with H&E, and immunostained with PAX-5, CD3, pancytokeratin (CK), vimentin, and Wilms tumor 1 protein (WT1) antibodies, according to the cytologic diagnoses. A histologic case series of confirmed normal, reactive, and neoplastic mesothelium and several different carcinomas were included to test the utility of WT1 as a marker of mesothelial cells. Results:CTBs had a layered appearance with reduced background staining. CD3 and PAX5 immunolabeling allowed immunophenotype assessment in all of the lymphoma cases. In carcinomatous effusions, neoplastic cells were CK-positive, WT1negative, and vimentin-negative (except for two cases). Wilms tumor 1 protein was positive in the nuclei of normal, reactive, and neoplastic mesothelial cells, and ovarian carcinomatous cells. Other carcinomas and lymphomas were negative. Conclusions:CTBs are valuable tools to assist in making a diagnosis of cavitary effusions in dogs and cats, and WT1 is a promising marker to differentiate mesothelial from carcinomatous cells. K E Y W O R D Scell blocks, cytology, effusion, immunohistochemistry, mesothelial cells

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

“…Conversely, in the CTB samples, the background material did not contribute to the CTB backgrounds because the samples were layered and separated from nucleated cells. These results confirmed that cell blocks could reliably be used in IHC studies of effusion samples 10,11,14,19,20 and suggested that routine IHC procedures used for tissue biopsies can be directly transferred to cell blocks.…”

“…The main limitation of this study is that non‐neoplastic and non‐hemorrhagic samples were not included because these effusion types are marginally involved in the ancillary testing of routine practices. Based on our experience and on data reported in the literature 14,20 we think that non‐neoplastic and non‐hemorrhagic effusions would behave similarly to other effusion types, as long as poorly cellular samples are concentrated, and high‐density solutions are used for CTBs in the absence of visible RBCs. Another possible limitation of this study is related to the aggregation media, as ACBs were produced with HistoGel in one center and Bio‐Agar in the other.…”

“…In the past few years, cell blocks have been increasingly used in veterinary cytology, particularly for IHC studies on several biologic matrices 14‐26 . Short protocols with low costs and minimal influences on laboratory workflow are the key reasons to introduce cell block technology for routine practice.…”

“…There has also been increasing interest in minimally invasive procedures and ancillary testing in diagnostic cytology. Cell blocks have been obtained from matrices, such as peripheral blood, 14‐16 cerebrospinal fluid, 14 synovial fluid, 14 bone marrow, 17,18 effusions, 19,20 urine, 14,21 fine‐needle aspiration rinses, 14,22‐25 and bronchoalveolar lavage fluids 14,26 . All described methods involve two distinct phases: preparation and processing.…”

Feline mesothelioma: case report and review of cytologic, immunocytochemical, histopathologic, and immunohistochemical findings

“…HBME1 and calretinin, 2 commonly used markers for human mesothelioma, were expressed in 7 of 11 and 0 of 10 feline mesotheliomas, respectively. 1,2,6,8,9,14,15,20 Reactive feline mesothelial cells have been found to label with WT1 protein, 10 prompting investigation of expression of this protein in our case. Most (~60-95%) mesothelioma cells in our case exhibited strong cytoplasmic labeling with WT1.…”