Introduction

Chondrosarcoma is a malignant neoplasm in which tumor cells produce varying amounts of neoplastic chondroid and fibrillar matrix but not osteoid. Chondrosarcoma is reported most frequently in the dog. In most other domestic species, chondrosarcoma is relatively rare. This short communication describes a peripheral chondrosarcoma in a 1.5-year-old Syrian Hamster and a review of our current understandings about chondrosarcoma in companion animals.

Clinical Presentation

A 1.5-year-old female Syrian hamster was referred due to a large subcutaneous mass stuck to the ribs. The animal was lethargic with very weak vital signs. Symptomatic treatment was done but the clinical signs deteriorated and the animal was euthanized. At necropsy a mass measured 3×4×5 cm³ weighing 55 grams was found. The mass was fixed in 10% neutral buffered formalin and processed routinely for H&E staining.

Results

Histopathological examination revealed chondrocytes of various sizes and shapes irregularly dispersed within an abundant chondroid matrix. Lacunae contained plump cells which had large nuclei and prominent nucleoli. There were abnormal giant chondrocytes showing pleomorphism and atypical mitotic figures. There were also necrotic foci associated with hemorrhage. Based on microscopic findings, the tumor was diagnosed as Grade II chondrosarcoma.

Discussion

Chondrosarcoma is a rare neoplasm in exotic pets and according to the literature, there are few reports regarding chondrosarcoma in hamster which have been reported in humerus and mandible. Chondrosarcoma most often is reported in dogs and there is very few information about chondrosarcoma in exotic pets.

Chondrosarcomas involve flat bones more often than long bones and may form large masses without surgical intervention. Rib tumors can produce pulmonary atelectasis because of their eccentric growth.

A primary chondrosarcoma arises either de novo within a bone organ (central or medullary chondrosarcoma) or from the periosteum (peripheral chondrosarcoma). In animals most chondrosarcomas are considered primary bone tumors of medullary origin, and primary chondrosarcomas of periosteal origin are rare in animals.

This case is a very rare report of chondrosarcoma in exotic pets and to the authors' knowledge, the first report of peripheral chondrosarcoma in a hamster.