Suspected Radiation-Induced Osteosarcoma in a Domestic Shorthair Cat

Valérie J. Poirier,Shannon Wainberg,Stephanie G. Nykamp,Natalie Swieton,Michelle L. Oblak

doi:10.1155/2020/1874342

Abstract

A 3-year-old, male neutered domestic shorthair cat, presented for acute onset tail paresis. He was diagnosed with a spindle cell tumour at the level of L7-CD1 and treated with course fractionation radiation therapy. Three years following radiation therapy, the cat developed chondroblastic osteosarcoma of the pelvis, suspected to be secondary to radiation therapy. Hemipelvectomy was performed and the cat was treated with radiation therapy for remaining gross disease. The cat was euthanized 127 days post-operatively due to suspected metastatic disease. Development of radiation-induced tumours should be considered as a rare late complication in cats undergoing radiation therapy.

Highlights

Primary bone tumours are rare in cats, occurring with an incidence of 4.9 of 100,000 individuals, with osteosarcoma (OSA) comprising 70–80% of these tumours [1, 2]. ese tumours can arise from any bone but are slightly more common from appendicular than axial skeletal sites, the proximal humerus, tibia, and distal femur [1]
One retrospective analysis described radiation-induced bone tumours in 8% of dogs treated at appendicular sites with de nitive orthovoltage radiation doses totalling 40–51 Gy [12]
Discussion is case report describes a unique occurrence of an OSA, which developed in the pelvis almost 3 years following radiation therapy for a primary spinal tumour. e young age of the patient, occurrence of two separate neoplasm types, site of development, and aggressive nature of the OSA make this case unusual

Summary

Introduction

Primary bone tumours are rare in cats, occurring with an incidence of 4.9 of 100,000 individuals, with osteosarcoma (OSA) comprising 70–80% of these tumours [1, 2]. ese tumours can arise from any bone but are slightly more common from appendicular than axial skeletal sites, the proximal humerus, tibia, and distal femur [1]. Radiation-induced bone tumours have been infrequently reported in humans and dogs [8,9,10]. One retrospective analysis described radiation-induced bone tumours in 8% of dogs treated at appendicular sites with de nitive orthovoltage radiation doses totalling 40–51 Gy [12].

Results

Conclusion