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extragnathic fibromyxoma of bone

Tuesday 1 February 2011

Definition: Extragnathic fibromyxoma of bone is a benign intraosseous tumor composed of fibrous tissue with a variable myxoid stroma. Lesions with abundant myxoid tissue have been designated as myxomas.

Fibromyxoma or myxorna of bone is an accepted entity in the jaw.

Extragnathic lesions are muchless common, and their existence is controversial.

About 50 cases have been reported (2011).

Clinical synopsis

- Extragnathic fibromyxoma occurs over a broad age range, affecting patients from 2 to 74 years of age. Most are between 10 and 20 years or older than 50 years.
- Sex ratio 1/1.
- Pain is the usual complaint.


There is a predilection for the metaphysis of long bones.

Lesions in the distal or proximal part of the femur comprise about one third of cases, followed by involvement of the proximal or distal tibia and other long tubular bones.


The tumor can be a well-marginated, lytic medullary defect or an expansile, bubbly lesion with cortical destruction and soft tissue extension.

Surrounding reactive bone is typically absent.


The excised tissue is usually gray or white, and varies from fibrous to gelatinous, slimy, or mucoid in consistency. Cystic areas may be noted in completely resected specimens.


- Loose myxoid arase alternats with more fibrotic ragions.
- Foci of dystrophie calcification are interspersed.


Fibromyxoma is a fibrous and myxoid neoplasm with both elements present to variable degrees.

The proliferating stromal cells may be spindle shaped or stellate.

Areas of chondroid, osteoid, densely mineralized bone, or dystrophie calcification are often interspersed.

The stroma’ cells associated with such foci do not differ from those in other fibromyxoid areas.

In the more myxoid areas, the stroma may be sparsely cellular.

The cell nuclei throughout the lesion are uniform and small, without evidence of pleomorphism or mitotic figures.

Lobulation is not present microscopically, and there is no surrounding fibrous capsule.

Secondary aneu¬rysmal bone cyst formation may be present.

Differential Diagnosis

- myxoid lesions of bone

  • chondromyxoid fibroma
  • chondrosarcoma

- intraosseous ganglion

Predominantly myxoid forms of fibromyxoma may be confused with an intraosseous ganglion, chondromyxoid fibroma, or chondrosarcoma.

Unlike fibromyxorna, an intraosseous ganglion is a purely cystic.

See also

- fibrous lesions of bone
- fibromyxoma of bone (myxoma of bone)

  • gnathic fibromyxoma of bone (gnathic myxoma of bone)