Performance of lymph node cytopathology in diagnosis and characterization of lymphoma in dogs

Abstract

Background Cytopathology is a minimally invasive and convenient diagnostic procedure, often used as a substitute for histopathology to diagnose and characterize lymphoma in dogs. Objectives Assess the diagnostic performance of cytopathology in diagnosing lymphoma and its histopathological subtypes in dogs. Animals One‐hundred and sixty‐one lymph node samples from 139 dogs with enlarged peripheral lymph nodes. Methods Based only on cytopathology, 6 examiners independently provided the following interpretations on each sample: (a) lymphoma vs nonlymphoma; (b) grade and phenotype; and (c) World Health Organization (WHO) histopathological subtype. Histopathology and immunohistochemistry (IHC) findings were used as reference standards to evaluate diagnostic performance of cytopathology. Clinical, clinicopathologic, and imaging data also were considered in the definitive diagnosis. Results Classification accuracy for lymphoma consistently was >80% for all examiners, whereas it was >60% for low grade T‐cell lymphomas, >30% for high grade B‐cell lymphomas, >20% for high grade T‐cell lymphomas, and <40% for low grade B‐cell lymphomas. Interobserver agreement evaluated by kappa scores was 0.55 and 0.32 for identification of lymphoma cases, and of grade plus immunophenotype, respectively. Conclusions and Clinical Importance Cytopathology may result in accurate diagnosis of lymphoma, but accuracy decreases when further characterization is needed. Cytopathology represents a fundamental aid in identifying lymphoma and can be used as a screening test to predict grade and phenotype. However, these results must be confirmed using other ancillary techniques, including flow cytometry, histopathology, and immunohistochemistry (IHC).

Clinical and Clinical Pathological Presentation of 310 Dogs Affected by Lymphoma with Aberrant Antigen Expression Identified via Flow Cytometry

“…Consequently, a high number of phenotypic aberrancies would be lost performing only IHC. Still, histopathology plus IHC remains the gold standard technique to classify canine lymphoma according to the WHO system [37]. Thus, we support the concomitant use of FC and IHC for more detailed characterization of canine lymphoma cases.…”

Clinical outcome and Ki67 evaluation in dogs with nodal small cell B‐cell lymphoma diagnosed by flow cytometry

“…Cell size as assessed by cytology can be a useful indicator that neoplastic cells are present but should not be used to predict biological behavior. A study assessing the performance of cytology to diagnose and characterize lymphoma in dogs revealed that cytology is useful in accurately diagnosing lymphoma, but accuracy decreases when attempting to predict grade and phenotype, and ancillary diagnostics must be used for further characterization 34 . The cases in this study had small cell size defined by flow cytometry FS.…”

“…A study assessing the performance of cytology to diagnose and characterize lymphoma in dogs revealed that cytology is useful in accurately diagnosing lymphoma, but accuracy decreases when attempting to predict grade and phenotype, and ancillary diagnostics must be used for further characterization. 34 The cases in this study had small cell size defined by flow cytometry FS. Though only 4 cases had histology, all 4 had lymphocytes described as small to intermediate in size.…”

Linfoma canino: estudo caso-controle na Região Metropolitana do Recife-PE, Brasil

“…Nos cães, o linfoma é comumente classificado com base nos achados citológicos, sendo a análise citopatológica de grande valia no diagnóstico de linfoma em cães (Martini et al, 2022). Duas principais classificações são utilizadas para o LC:…”