Fibrosarcoma of the bone

Fibrosarcoma of the bone is a rare malignant bone tumor which may occur as a primary lesion, or secondarily after radiation treatment, dedifferentiation from other tumors 3 or pathologies such as Paget disease, bone infarction, or chronic osteomyelitis.

It is a distinct entity from but similar to malignant fibrous histiocytoma 2 that may also rarely occur in bone, causing confusion in terminology as the term "fibrosarcoma" has in the past encompassed a multitude of distinct histologic diseases. 

Fibrosarcoma occurs primarily in the 30-60 year olds, with a slight male predominance. It constitutes <5% primary bone tumors. Infantile fibrosarcoma is also rarely encountered in bone.

Cells are fibroblastic in appearance with a somewhat uniform spindle shape. They may be arranged in fascicles creating a herringbone pattern. The degree of differentiation is variable, however, and therefore distinguishing features from other spindle cell neoplasm should be sought. Extracellular collagen fibrils are typical. 

Plain radiograph

Typically highly destructive with a wide zone of transition, and occasionally expansile. Periosteal reaction is uncommon, but if seen is usually laminated, spiculated or Codman triangles. The lesion usually has no matrix mineralisation, but may have areas of sequestered bone. These tumors are often associated with a large soft tissue mass extending from the bone 1.

MRI

MRI is useful in defining intraosseous spread and the extent of extension into the soft tissues. Descriptions of the appearance of intraosseous fibrosarcoma on MR are few. 

Signal characteristics

The signal intensity pattern is nonspecific:

  • T1: isointense to muscle
  • T2: hyperintense to muscle
  • T1C+: avid contrast enhancement (may be uniform or heterogeneous)

Bone tumours

The differential diagnosis for bone tumours is dependent on the age of the patient, with a very different set of differentials for the paediatric patient.

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Article Information

rID: 27312
Section: Pathology
Tag: cases
Synonyms or Alternate Spellings:
  • Fibrosarcoma of bone
  • Fibrosarcoma (bone)
  • Osseous fibrosarcoma

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