MALIGNANT TRANSFORMATION OF SOLITARY SPINAL OSTEOCHONDROMA IN TWO MATURE DOGS

Canine osteochondroma is an uncommon bony tumor that arises in skeletally immature animals. Consequently, clinical signs typically occur in young dogs as a result of impingement of normal structures by the tumor. Radiographically, osteochondromas are benign in appearance. They are well circumscribed and cause no bony lysis nor periosteal proliferation. Osteochondromas may occur in two forms; solitary or multiple. Although histology and biologic behavior are identical, when in the multiple form the condition has been termed multiple cartilaginous exostoses. Malignant transformation of multiple cartilaginous exostoses has been reported in three mature dogs. We report two dogs with malignant transformation of solitary spinal osteochondromas. Both underwent transformation to osteosarcoma. Despite the benign radiographic appearance of osteochondromas and multiple cartilaginous exostoses, clinical signs should alert the clinician to the possibility of malignant transformation.     

Multiple cartilaginous exostoses in a dog

A case of multiple cartilaginous exostoses (osteochondromatosis) in a 9-month-old Kelpie cross dog is described. This uncommon dyschondroplasia, which resembled multiple cartilaginous exostoses in man, involved the radius, the femur, a metacarpal and metatarsal bone, the phalanges of three extremities, the pelvis, the ribs and cervical, thoracic and coccygeal vertebrae.     

Multiple cartilaginous exostoses with development of a metastasizing osteosarcoma in a Shetland Sheepdog

A case of multiple cartilaginous exostoses in an 8-year-old Shetland Sheepdog is described. One of the exostoses on the left scapula transformed into an osteosarcoma which metastasized to the lungs. This finding is unusual as in many cases described in man and in one case in a dog chondrosar-comas developed from the exostoses.
Résumé. L'article porte sur un chien berger (Shetland) age de huit ans, présentant des exostoses cartilagineuses multiples. Un exostose de l'omoplate gauche s'est transformé en osteosarcome avec des metastases aux poumons. Ceci semble rare parce que de nombreux études chez l'homme et le seul ches cité chez un chien demontrent le developpement de chondrosarcomes.
Zusammenfassung. In diesem Artikel wird ein Fall der multiple knorplige Exostosen bei einem acht jährigem Shetland Schäferhund beschrieben.
Aus eine Exostose an der lenkin Scapula entwickelte sich ein Osteosarkom der zur Lunge metastasierte. Dieser Befund ist unbewöhnlick da in vielen Fällen die beim Menschen beschrieben wurden und in eimem Fall der beim Hund beschrieben wurde Chondrosarkomata sich aus multiple knorplige Exostosen entwickeln.     

RADIOGRAPHIC DIAGNOSIS: CARTILAGINOUS EXOSTOSES IN A DOG

A 6 month-old dog was examined for progressive paraparesis. On physical examination bony malformations were palpated over the cranial lumbar vertebral bodies and on the left metatarsal bone. Neuroanatomic lesion localization for the paraparesis was a T3-L3 spinal cord lesion. Radiographs confirmed bony masses at L1-L2 and on the left 3rd metatarsal bone. Magnetic resonance imaging was performed from T3-L3. Severe spinal cord compression was identified at L1-L2. Surgical decompression and biopsy confirmed the mass to be cartilaginous exostoses. This paper is an example of cartilaginous exostoses imaged with MR.