A Morphological Study of 608 Cases of Canine Malignant Lymphoma in France With a Focus on Comparative Similarities Between Canine and Human Lymphoma Morphology

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BlankA Morphological Study of 608 Cases of Canine Malignant Lymphoma in France

With a Focus on Comparative Similarities Between Canine and Human Lymphoma

Morphology

1.. F. Ponce1,

2.. T. Marchal1,

3.. J. P. Magnol1,

4.. V. Turinelli1,

5.. D. Ledieu1,

6.. C. Bonnefont1,

7.. M. Pastor1,

8.. M. L. Delignette2 and

9.. C. Fournel-Fleury1

+ Author Affiliations

1.. 1Laboratoire de Pathologie Clinique et Unité d’Oncologie, Ecole Nationale

Vétérinaire de Lyon, France

2.. 2Unité de Biomathématiques, Ecole Nationale Vétérinaire de Lyon, France

1.. Frédérique Ponce, Unité de Médecine Interne, Ecole Nationale Vétérinaire

de Lyon, 1 Avenue Bourgelat, 69280 Marcy L’Etoile, France Email:

f.ponce@...

Abstract

This study reports cytomorphological, histomorphological, and immunological

characterization of 608 biopsy cases of canine malignant lymphoma, with

epidemiological and clinical data, collected from 7 French veterinary pathology

laboratories. It compares morphological characteristics of malignant lymphoma in

canines, per the updated Kiel classification system, with those reported in

humans, per the World Health Organization (WHO) classification system. Of tumors

described, 24.5% and 75.5% were classified as low- and high-grade malignant

lymphomas, respectively. Presenting clinical signs included generalized or

localized lymphadenopathy (82.4%) and extranodal diseases (17.6%) involving the

skin (12.34%) and other sites (5.26%). Immunohistochemistry confirmed 63.8%

B-cell (CD3–, CD79a+), 35.4% T-cell (CD3+, CD79a–), and 0.8% null-cell (CD3–,

CD79a–) lymphomas. Most B-cell cases (38.49%) were of high-grade centroblastic

polymorphic subtype; most T-cell cases (8.55%), high-grade pleomorphic mixed and

large T-cell lymphoma subtypes. Some B-cell tumors showed morphologic

characteristics consistent with follicular lymphomas and marginal zone lymphomas

per the Revised European American Classification of Lymphoid Neoplasms and WHO

canine classification systems and the WHO human classification system. Unusual

high-grade B-cell subtypes included an atypical high-grade small B-cell lymphoma

(0.66%), Burkitt-type B-cell lymphoma (1.64%), plasmacytoid lymphoma (0.99%),

and mediastinal anaplastic large B-cell lymphoma (0.16%). Unusual T-cell

subtypes included a previously undescribed high-grade canine immunoblastic

T-cell type (1.15%), a rare low-grade prolymphocytic T-cell lymphoma (0.16%),

and a recently described high-grade canine T-cell entity—aggressive granulocytic

large-cell lymphoma (0.16%). Marginal zone lymphomas were common (10.86%);

follicular lymphomas were rare (0.49%). Canine primary cutaneous malignant

lymphoma subtypes were present (11.84%). There was no significant difference

between B- and T-cell malignant lymphoma in regard to canine age and sex. A

significant overrepresentation of Boxers (24.19%) was found for T-cell

lymphomas.