Chondromyxoid fibroma
Synonyms and keywords:

# Overview
Chondromyxoid fibroma is a rare benign bone tumor accounting for approximately 1% of all benign bone tumors. Chondromyxoid fibroma affects all age groups. It is more commonly seen during the second and third decades of life. Men are more commonly affected than women. Chondromyxoid fibroma arising from the physeal remnant is the commonly proposed theory in the pathogenesis of this tumor. It is predominantly found in the metaphyses of the long bones. The bones involved include tibia, distal femur, pelvis, feet and hands. Chromosome 6 appears to be involved in chondromyxoid fibroma. Over expression of the glutamate receptor gene GRM1 in patients with chondromyxoid fibroma via promoter swapping and gene fusion has been observed. The hallmark of chondromyxoid fibroma is pain, swelling, and pathological fracture. The mainstay of treatment for chondromyxoid fibroma is surgery (curettage and bone grafting).

# Historical Perspective
In 1948, Jaffe and Lichtenstein described chondromyxoid fibroma for the first time.

# Classification
Chondromyxoid fibroma can be classified based on imaging findings.

## Enneking (MSTS) Staging System
- The Enneking surgical staging system (also known as the MSTS system) for benign musculoskeletal tumors is based on radiographic characteristics of the tumor host margin.
- It is widely accepted and routinely used classification.

# Pathophysiology
- The exact etiology of chondromyxoid fibroma is unknown.
- Chondromyxoid fibroma arising from the physeal remnant is the commonly proposed theory in the pathogenesis of chondromyxoid fibroma.
- It is predominantly found in the metaphyses of the long bones.
- The bones involved by chondromyxoid fibroma includes tibia, distal femur, pelvis, feet and hands.

## Genetics
- Chromosome 6 appears to be involved in chondromyxoid fibroma.
- The non-random clonal abnormalities involves 6p25, 6q13 and 6q23.
- Whole-genome mate-pair sequencing and RNA sequencing showed over expression of the glutamate receptor gene GRM1 in patients with chondromyxoid fibroma via promoter swapping and gene fusion.

# Causes
There are no established causes of chondromyxoid fibroma.

# Differentiating Chondromyxoid Fibroma from Other Diseases
Chondromyxoid fibroma must be differentiated from the following bone disorders:

# Epidemiology and Demographics
- Chondromyxoid fibroma is a rare benign bone tumor accounting for approximately 1% of all benign bone tumors.
- Chondromyxoid fibroma affects all age groups.
- It is more commonly seen during the second and third decades of life.
- Men are more commonly affected than women.
- There is no racial predilection to chondromyxoid fibroma.

# Risk Factors
There are no established risk factors for chondromyxoid fibroma.

# Screening
There is insufficient evidence to recommend routine screening for chondromyxoid fibroma.

# Natural History, Complications, and Prognosis
Common complications of chondromyxoid fibroma include:
- Pathological fracture
- Premature epiphyseal closure
- Limb-length discrepancy
- Angular deformity
Prognosis is generally good for chondromyxoid fibroma.
- Prognostic variables include:
Children
When the Tumor is more lobulated with abundant myxoid material
- Children
- When the Tumor is more lobulated with abundant myxoid material

# Diagnosis

## Diagnostic Study of Choice
- Biopsy is the diagnostic study of choice for chondromyxoid fibroma.
- Biopsy findings under low and high power fields are given below:
- It has a biphasic appearance
- It has lobules and pseudolobules of fibromyxoid tissue with hypercellular area.
- The cells are spindle-shaped or stellate-shaped and contain hyperchromatic nuclei.
- Multinucleated giant cells and fibrovascular tissue may be present between the lobules.
- Hypocellular area with chondroid material is seen.
- The tumor shows myxoid stroma mixed with stellate cells.
- In addition, an area of pleiomorphic cells with bizarre nuclei may be seen.

## History and Symptoms
- The majority of patients with chondromyxoid fibroma have a positive history of:
Pain
Swelling
Stiffness
Pathological fracture
- Pain
- Swelling
- Stiffness
- Pathological fracture

## Physical Examination
Common physical examination findings of chondromyxoid fibroma include:
- Deformity
- Swelling
- Decreased range of motion
- Warmth over the affected area

## Laboratory Findings
There are no diagnostic laboratory findings associated with chondromyxoid fibroma.

## Electrocardiogram
There are no ECG findings associated with chondromyxoid fibroma.

## X-ray
X-ray findings include:
- The tumor appears as a lytic, eccentric metaphyseal lesion.
- Size of the lesion may vary from 2 to 10 cm.
- It has a sharply demarcated border from the adjacent bone.
- It may show scalloped and sclerotic rim
- Calcification is usually not seen
- The tumor may show cortical expansion.

## Echocardiography or Ultrasound
There are no echocardiography/ultrasound  findings associated with chondromyxoid fibroma.

## CT scan
- CT scan confirms the x-ray findings.
- It is superior to x-ray for analyzing the expansion of the lesion and cortical breach.

## MRI
MRI findings of chondromyxoid fibroma include:
- T1 image: Chondroid and myxoid tissues produce low signals.
- T2 image: Chondroid and myxoid tissues produce high signals.

## Other Imaging Findings

## Bone Scan
- Increased uptake is seen in chondromyxoid fibroma.

## Other Diagnostic Studies
There are no other diagnostic studies associated with chondromyxoid fibroma.

# Treatment

## Medical Therapy
There is no treatment for chondromyxoid fibroma; the mainstay of therapy is surgery.

## Surgery
Surgery is the mainstay of treatment for chondromyxoid fibroma.
Types
1. Intralesional Curettage
- It is the mainstay of treatment for chondromyxoid fibroma.
- The defect is filled with bone graft or bone cement in form of polymethlymethacrylate(PMMA).
2. En Bloc Excision
- It usually reserved for recurrent cases.
Recurrence Rate
- The recurrence rate is about 25% for chondromyxoid fibroma.

## Primary Prevention
There are no established measures for the primary prevention of chondromyxoid fibroma.

## Secondary Prevention
There are no established measures for the secondary prevention of chondromyxoid fibroma.