Comparison of Diagnostic Utilities in a Canine Retrobulbar Large B-Cell Lymphoma With Multifocal Involvement

Sep 30, 2026

Lymphoma is the most common malignant neoplasm in dogs, yet retrobulbar lymphoma is seldom documented. An 8-year-old neutered male Shih Tzu presented with bilateral exophthalmos; computed tomography and magnetic resonance imaging identified bilateral retrobulbar masses plus salivary gland and cranial mediastinal enlargement. Histopathology and immunohistochemistry confirmed large B-cell lymphoma. Cytology showed intermediate-to-large malignant lymphocytes as the dominant retrobulbar population (>80%) with lower proportions elsewhere. Flow cytometry and antigen receptor rearrangement polymerase chain reaction supported a B-cell origin, while heterogeneous populations were noted in other affected sites.

LanguageEnglish

CategoryHealthcare

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Abstract

Introduction

Case Presentation

Veterinary Medicine and Science CASE REPORT Comparison of Diagnostic Utilities in a Canine Retrobulbar Large B-Cell Lymphoma With Multifocal Involvement Rankyung Jung Hyeona Bae Kyu-Woan Cho Dong-In Jung DoHyeon Yu College of Veterinary Medicine, Gyeongsang National University, Jinju, South Korea Correspondence: DoHyeon Yu ([yudh@gnu.ac.kr](yudh@gnu.ac.kr)) Received: 28 November 2024 Revised: 27 September 2025 Accepted: 11 December 2025 Keywords: flow cytometry | immunohistochemistry | large B-cell lymphoma | ocular lymphoma | polymerase chain reaction for antigen receptor rearrangement | retrobulbar lymphoma ABSTRACT Lymphoma is the most common malignant neoplasm in dogs. However, retrobulbar lymphoma, a type of orbital lymphoma, is rarely reported in dogs. An 8-year-old neutered male Shih Tzu dog presented with bilateral exophthalmos. Computed tomography and magnetic resonance imaging revealed bilateral retrobulbar masses and enlargement of the salivary glands and cranial mediastinum. Histopathological examination and immunohistochemistry of the retrobulbar tissue confirmed large B-cell lymphoma. On the cytologic analysis, intermediate-to-large malignant lymphocytes were predominant in the retrobulbar tissue (>80%); however, they accounted for 30%–50% of the cranial mediastinum, submandibular lymph nodes and salivary glands. Flow cytometry of the retrobulbar lesion showed a B-cell phenotype (cluster of differentiation [CD]3 − /CD4 − /CD5 − /CD8 − /CD21+ /CD34 − /CD79a+ /major histocompatibility complex II), whereas the cranial mediastinum, submandibular lymph node and salivary gland exhibited a heterogeneous cell population. Polymerase chain reaction for antigen receptor rearrangement demonstrated clonality with immunoglobulin gene rearrangement, indicating a B-cell origin. Chemotherapy with l-asparaginase, vincristine, cyclophosphamide, doxorubicin and prednisone was initiated; however, neurological symptoms developed after the first cycle. Subsequent cerebrospinal fluid cytology and flow cytometry suggested central nervous system involvement in the lymphoma, and the dog was euthanized owing to disease progression despite the addition of lomustine. To our knowledge, this is the first report of bilateral retrobulbar large B-cell lymphoma with multifocal involvement in a dog. A comprehensive assessment of diagnostic modalities is essential to diagnose extranodal lymphoma and assess extranodal involvement. 1 Introduction Lymphoma is the most common malignant neoplasm in dogs, accounting for 7%–24% of all canine tumours and 83% of haematopoietic malignancies (Vail et al. 2019) . On the basis of their site of occurrence, they are classified into two forms: Multicentric form is characterized by peripheral lymphadenopathy, whereas the extranodal form affects various organs apart from the lymphatic system, including the mediastinum, gastrointestinal tract, liver, spleen, kidneys, skin, eyes, central nervous system (CNS) and lungs (Natthanet Sritrakoon et al. 2016) . Ocular lymphoma affects the eyelid, conjunctiva, lacrimal sac or gland, orbit and intraocular tissues (Sritrakoon et al. 2018) . Although secondary ocular involvement is common in canine multicentric lymphoma, primary ocular lymphoma, particularly the retrobulbar region, is rarely reported in dogs and cats (Aquino et al. 2000; Wiggans et al. 2014) . The retrobulbar space comprises the extraocular muscles, lacrimal glands, zygomatic salivary glands, masticatory muscles, This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. © 2026 The Author(s) . Veterinary Medicine and Science published by John Wiley & Sons Ltd. Veterinary Medicine and Science, 2026; 12:e70783 1 of 6 [https://doi.org/10.1002/vms3.70783](h

FAQs

What clinical signs and imaging findings were observed in the dog?

The dog showed bilateral exophthalmos. CT and MRI revealed bilateral retrobulbar masses along with enlargement of the salivary glands and cranial mediastinum.

How was large B-cell lymphoma confirmed?

Histopathological examination and immunohistochemistry of retrobulbar tissue confirmed large B-cell lymphoma.

Which diagnostic tests were used to assess cellular phenotype and clonality?

Flow cytometry characterized a B-cell phenotype in the retrobulbar lesion, and polymerase chain reaction for antigen receptor rearrangement demonstrated clonality with immunoglobulin gene rearrangement.

Sep 30, 2026

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