Osteochondromatosis

From Dog

Osteochondromatosis is a rare benign idiopathic cartilage disease of young, large-breed dogs characterized by growth-plate cartilage proliferation[1].

The disease arises from a defect in the perichondrial ring, from physical stresses causing proliferative responses at the margin of the physis, or from some form of periosteal disturbance that induces perichondrial growth. These growth may transform into malignant chondrosarcomas[2].

Any bone of endochondral origin may be affected; however, in decreasing frequency, vertebrae (especially spinous processes, but also body and arch), ribs, long bones, feet and pelvis are most often involved in dogs. Growth of osteochondromas in dogs typically ceases at the time of skeletal maturation, although occasionally, some may progress after skeletal maturity[3].

Osteochondromatosis is frequently a subclinical condition diagnosed as an incidental radiographic finding. However, neurological signs occasionally occur in animals associated with spinal cord compression secondary to vertebral osteochondromas in any region of the spinal column, but most commonly cervical and/or thoracic areas[4][5].

Clinically affected dogs present with limb lameness, ataxia and proprioceptive deficits. Signs observed will depend on the location of the masses (e.g., cervical syndrome, cervicothoracic syndrome, and thoracolumbar syndrome). There may be variable signs of pain on palpation of the thoracic or cervical spine.

Radiography usually reveals joint exostoses, large, smoothly contoured cystic bony masses, with irregular or well-delineated borders, sometimes with mottled patterns of radiolucency and radiodensity[6]. Fusion of vertebrae at articular facets in the presence of normal intervertebral disks, may be observed[7]. Microscopic examination of a biopsy specimen, which includes the cartilage cap and bony stalk covered by a membrane continuous with the periosteum, will confirm the diagnosis.

Surgical excision (including removal of the perichondrial membrane on the surface of the cartilage cap), spinal cord decompression, and perhaps vertebral stabilization, are necessary in animals with clinical evidence of spinal cord attenuation.

Prognosis is guarded, especially in young animals with osteochondromas involving multiple vertebral sites where subclinical masses may assume importance as they grow until the skeleton matures. Early surgical removal may eliminate development of clinical complications.

References

  1. Pool RR. (1993) Osteochondromatosis. In: Bojrab MJ, Smeak DD, Bloomberg MS, ed. Disease mechanisms in small animal surgery. 2nd ed. Philadelphia: Lea & Febiger, pp:821-833
  2. Aeffner F et al (2012) Synovial osteochondromatosis with malignant transformation to chondrosarcoma in a dog. Vet Pathol 49(6):1036-1039
  3. Jacobson LS, Kirberger RM. (1996) Canine multiple cartilaginous exostoses: unusual manifestations and a review of the literature. J Am Anim Hosp Assoc 32:45-51
  4. Beck JA, Simpson DJ, Tisdall PL. (1999) Surgical management of osteochondromatosis affecting the vertebrae and trachea in an Alaskan Malamute. Aust Vet J 77:21-23
  5. Caporn TM, Read RA. (1996) Osteochondromatosis of the cervical spine causing compressive myelopathy in a dog. J Small Anim Pract 37:133-137
  6. Pool RR. (1993) Osteochondromatosis. In: Bojrab MJ, Smeak DD, Bloomberg MS, ed. Disease mechanisms in small animal surgery. 2nd ed. Philadelphia: Lea & Febiger, pp:821-833
  7. Jacobson LS, Kirberger RM. (1996) Canine multiple cartilaginous exostoses: unusual manifestations and a review of the literature. J Am Anim Hosp Assoc 32:45-51