+ General Considerations

  • 2 forms: single (= osteochondroma) or multicentric (= osteochondromatosis)
  • Multiple cartilaginous exostoses occurs after skeletal maturity in cats
  • Mean age 3.2 years
  • No breed or sex predisposition ± Siamese cats
  • Etiology: familial or viral with nearly all cats are FeLV-positive)
  • Multiple cartilaginous exostoses are rarely symmetrical and do not affect long bones, in contrast to dogs
  • Common sites: scapula, vertebrae, and mandible
  • FeLV-induced multiple cartilaginous exostoses are rapidly progressive with firm, painful swellings
  • Survey Radiographs: sessile or pedunculated protuberances from bony surfaces with indistinct borders, loss of smooth contour, and evidence of lysis, particularly with malignant transformation
  • Lesions are composed of hard irregular exostoses with a fibrous and cartilaginous cap
  • Endochondral ossification extends from the cap for a variable thickness
  • Complete surgical resection is difficult as the cap tends to blend with adjacent tissue
  • Surgery is indicated for palliation but recurrence is common
  • Multiple cartilaginous exostoses have an aggressive biologic behaviour with potential for malignant transformation and metastases