Iliac osteosarcoma

Case contributed by Dr Dayu Gai

Presentation

Incidental finding post trauma

Patient Data

Age: 17
X-ray

Large lytic lesion in the left iliac crest, with relatively narrow zone of transition. No soft tissue component identified. No pathological fracture. Intravesical contrast from contrast enhanced CT study (see below).

CT

CT confirms a 7 x 2 x 4 cm lytic lesion in the left iliac crest.

FDG PET/CT performed a period of time after the initial study. The expansile lesion has grown in size, with a rim of FDG avidity which protrudes into the ipsilateral iliacus muscle, concerning for an aggressive lesion.

Case Discussion

Biopsy was performed.

Microscopic description:

Core biopsies show variably cellular proliferation of osteoblastic cells set in variable stroma with some areas of osteoid production. Some fibromyxoid stroma is noted and an occasional figure is seen.

Opinion:

Core biopsies from left iliac crest lesion - the features are of conventional type osteosarcoma.

Osteosarcoma is an aggressive osseous malignancy, with osteoid matrix. The vast majority are of unknown aetiology and considered primary (like this case). A small proportion of secondary osteosarcoma are due to genetic mutation, such as Retinoblastoma gene, or other disease processes such as Paget disease.

Note that in the initial radiograph and CT, this case lacked many of the stereotypical aggressive features - periosteal reaction, broad zone of transition, soft tissue mass.

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Case information

rID: 54182
Case created: 26th Jun 2017
Last edited: 26th Jun 2017
Inclusion in quiz mode: Included

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