Desmoplastic Fibroma of Sacroiliac Joint -MRI

34 yrs old male with biopsy proven desmoplastic fibroma of  Sacroiliac joint region on left , presented with chronic pain with no trauma. MRI shows heterogeneous mildly  expansile  complex  lesion with oedematous,  intraosseous components with poorly defined margins   with  creeping appearance with no subluxation, new bone formation,  soft tissue collections, vessel encasement  and lymphadenopathy 

Teaching points 

By  Mr Narasimhulu (MRI Tech) & Dr MGK Murthy 

1.Rare locally aggressive bone neoplasm (0.11% in some series of primary bone neoplasms) 

2.Histologically resembles extra abdominal desmoid tumour  with spindle cells with cytological atypic and abundant cytoplasm

3.Most common  in mandible and long bones metaphysis

4. CT is preferred method to visualise intra osseous extension and cortical breach . CT suggests minor pseudo trabeculation and marginal sclerosis. MR is preferred to exclude extra osseous components  

5. Young and middle age involved (M=F)

6.Malignant potential exists but very unlikely 

7. Resection with wide margin preferred , but curettage and Grafting is  well accepted with recurrence rate of 50% which can again be treated 

8.Differentials on Imaging include fibrous dysplasia, giant cell tumor, simple bone cyst, aneurysmatic bone cyst, chondromyxofibroma, non-ossifying fibroma, eosinophilic granuloma, adamantinoma, and metastases.