Osteochondroma- Cartilage Cap Exostosis Causes,Diagnosis and Treatment

 

 

Definition- 

 Small over growth at the edge of physeal plate with endochondral ossification

 develops into a bony protuberance covered by cartilage cap.

 

Type-      

Solitary, Multiple (HME),

Sessile(broad base), Pedunculated (Narrow base)

 

Clinical Feature:

  One of the commonest benign bone tumour,

  Common site--any bone may involved, fast   growing end of long bone, Iliac Crest

 Age-Teenager, young adult (any growth after   growth period-indicates-suggestive

  of malignant   transformation.

 

•Lump,

•Pain

•Paresthesia (rare)

•Multiple exostosis--when develop as a part of hereditary  disorder.

 

X-ray- 

          Appearence is pathognomic,-

            Well defined exostosis at metaphyses,

Looks smaller than feels,

Large lesion shows exostosis surrounded by clouds of calcified materials.

 

 

Pathogenesis:

           The pathogenesis of osteochondroma involves a genetic mutation leading to 

            abnormal bone and cartilage growth.

 

There is abnormal endochondral ossification in the region where the

 osteochondroma forms.

 

Under the influence of abnormal signaling Chondrocytes may fail to interact

properly with the surrounding periosteum, 

Abnormal proliferation of cells in the metaphyseal region.

 

Gene mutation in one of two gene -EXT1 Or EXT2. EXT1 located in chromosome

8q24.11-q24.13,And EXT2 located in chromosome 11p11-12.

 

 

Pathology-

 

At operation-cartilage cap is seen surmounting a narrow base or pedicle, cap is

hyaline cartilage,

Large lesion-Cowliflower appearence,degeneration and calcification in centre of

cartilage

The cartilage cap contains  chondrocytes. With variations in size and shape,  in a

columnar cell fashion and Lack of Cellular Atypia.

Cancellous Bone Core

Periosteal Reaction (optional)

 

Treatment:

 

Symptomatic- Excision,

Rapid enlarging-Urgent operation,

If any suspicion- Imaging and Staging and Biopsy,

If features like a benign lesion but certain to be enlarging- treat as

chondrosarcoma.

 

Complication:

 

Chance of malignancy -

1% in solitary lesion,

6% in multiple lesion.

 

 

Signs of malignant transformation-

 

Rapid and progressive enlargement,

Bulky cartilage cap,

Scattered flecks of calcification in cartilage cap,

Soft tissue spreading.