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Osteochondroma - pelvis

Case contributed by Assoc Prof Frank Gaillard


Childhood scoliosis surgery. Now right sided lump.

Patient Data

Age: 20 years
Gender: Female

Spine and pelvis x-rays

A lesion arising from the posterior medial aspect of the right iliac crest is noted which appears to abut the the underlying iliac crest, although its exact relationship to it is difficult to discern. It has an irregular outline with calcific / ossified components. The sacroiliac joint and L5/S1 disc space appear normal. Previous scoliosis surgery noted. 


CT pelvis

Multi-lobulated osseous mass, the medullary cavity of which is continuous with the superior aspect of the right iliac crest, just next to the sacroiliac joint is present. The largest component extends into the lateral right paraspinal muscles. A large soft tissue mass is not seen. No fracture of the lesion is detected. There is degenerative change in the right sacroiliac joint, with subchondral cysts formed inferiorly.


MRI pelvis

A large multiloculated osteochondroma arises from the posterior right iliac crest, with a small portion extending into the superior portion of the sacroiliac joint, but the main part extends to the lateral right paraspinal muscles. The cartilage cap is identified on all portions and measures no more than 5 mm thick. Post contrast administration, patchy enhancement  within the osseous component of the osteochondroma particularly posteriorly, is of uncertain significance. No fracture of the osseous component (including the stalk) and no bursa is seen. There is no soft tissue mass.  Degenerative change is seen in the right sacroiliac joints with small subchondral cysts formed inferiorly. No mass is seen in the pelvis. A cyst anterior to the right ovary is likely to be functional.

This patient went on to have this mass resected. 


MACROSCOPIC DESCRIPTION: A nodular portion of bulbous bone measuring 60x50x50mm.  The cartilage cap measures up to 8mm thick.  There are no suspicious features seen. 

MICROSCOPIC DESCRIPTION: The lesion is covered by a cap of hyaline cartilage, with underlying endochondral ossification.  Mature cortical and medullary bone is present adjacent to the cartilage cap and normal haemopoietic marrow is present in the intertrabecular spaces.  There is no evidence of malignancy.

FINAL DIAGNOSIS: Lesion right ilium:  osteochondroma.

Case Discussion

This case illustrates the typical appearances of a pedunculated osteochondroma without significant cartilage thinning and no evidence of secondary malignant degeneration. 

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Case information

rID: 16302
Published: 8th Jan 2012
Last edited: 13th Aug 2019
Inclusion in quiz mode: Included

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