Thymic epithelial tumours in 51 dogs: Histopathologic and clinicopathologic findings

Yale, AD; Priestnall, SL; Pittaway, R; Taylor, AJ

Abstract

Canine thymic epithelial tumours (TET) are uncommon and little is known about their behaviour. Previous attempts at histologic classification have varied, and as such reliable prognostic information is unavailable. The aim of this retrospective multi-institutional study was to evaluate cases of canine TETs, irrespective of subtype, in order to identify useful histopathologic and clinicopathologic prognostic factors. Cases were included if the tumour arose from the cranial mediastinum and a diagnosis of TET was made on the basis of histopathology. Fifty-one dogs were included. In addition to clinicopathologic data, histology samples were reviewed for the following features: mitotic count, percentage of necrosis, presence of Hassall's corpuscles, lymphocytic infiltrate, cellular pleomorphism and vascular or capsular invasion. The median survival time for all dogs was 449 days. The 1- and 2-year survival rate was 52.6% and 26.3% respectively. On multivariable analysis surgical excision of the thymic tumour was associated with significantly prolonged survival; the presence of metastasis, myasthenia gravis and moderate or marked cellular pleomorphism were associated with significantly reduced survival. Additional studies are needed to further evaluate prognostic factors to aid treatment recommendations.

Citation

Yale, A., Priestnall, S., Pittaway, R., & Taylor, A. (2021). Thymic epithelial tumours in 51 dogs: Histopathologic and clinicopathologic findings. Veterinary and Comparative Oncology, https://doi.org/10.1111/vco.12705

• Journal Article Type: Article
• Acceptance Date: May 9, 2021
• Publication Date: May 25, 2021
• Deposit Date: May 24, 2022
• Publicly Available Date: May 25, 2022
• Print ISSN: 1476-5810
• Publisher: British Veterinary Oncology Study Group
• Peer Reviewed: Peer Reviewed
• DOI: https://doi.org/10.1111/vco.12705
• Keywords: cancer; canine; thymic carcinoma; thymic epithelial tumour; thymoma; HEALTH-ORGANIZATION CLASSIFICATION; CARCINOMA REFINED DEFINITIONS; HISTOLOGICAL CLASSIFICATION; PARANEOPLASTIC SYNDROMES; RADIATION-THERAPY; ITMIG CONSENSUS; THYMOMA; CATS; SYSTEM; LYMPH