eMedicine Specialties > Orthopedic Surgery > Neoplasms

Chondromyxoid Fibroma: Differential Diagnoses & Workup

Author: Hannah D Morgan, MD, Consulting Staff, Connecticut Orthopaedic Specialists
Coauthor(s): Timothy A Damron, MD, David G Murray Endowed Professor, Department of Orthopedic Surgery, Professor, Orthopedic Oncology and Adult Reconstruction, Vice Chair, Department of Orthopedics, State University of New York Upstate Medical University at Syracuse
Contributor Information and Disclosures

Updated: Jan 18, 2008

Differential Diagnoses

Chondroblastoma
Chondrosarcoma

Other Problems to Be Considered

Chondrosarcoma (conventional)

Although chondrosarcoma may mimic CMF histologically, it typically has distinguishing demographic and radiographic characteristics. The peak incidence of chondrosarcoma occurs in the sixth and seventh decades of life, while CMF develops in the second and third decades. Radiographically, chondrosarcoma tends to be central and to have abundant calcifications. These characteristics also help to distinguish it from CMF. Chondrosarcoma and CMF, however, may each have mild expansion of cortical bone. In higher grade or long-standing chondrosarcoma, a soft-tissue mass may be observed. This mass is uncommon in CMF.^12,13

The histopathologic features of CMF—including a lobular growth pattern, occasional focal deposits of hyaline cartilage, rare mitotic figures, and even cellular pleomorphism—may be similar to those of chondrosarcoma. However, mucinous material, prominent nuclear atypia, and multiple pleomorphic or multinuclear cartilage cells all suggest chondrosarcoma. In addition, chondrosarcoma tends to behave in a more malignant fashion, having more severe symptoms, as well as faster growth, extraosseous invasion, and metastases, than does CMF.

Chondroblastoma

Chondroblastoma and CMF typically occur in individuals of the same age group and may have very similar histologic features, including chondroblastic differentiation, numerous giant cells, and a markedly positive S-100 stain result. Thus, chondroblastoma may be very difficult to distinguish from CMF. However, several features of chondroblastoma vary from those of CMF. The former typically occurs in an epiphyseal location, whereas CMFs are usually metaphyseal tumors. Moreover, microscopic calcifications, commonly found in chondroblastoma, are usually absent in CMF. Finally, the myxoid pseudolobulations that are noted in CMF are not observed in chondroblastoma.¹⁴

Nonossifying fibroma

These lesions tend to have a metaphyseal or diaphyseal location and an eccentric lytic appearance like that of CMF. However, nonossifying fibromas have a more marked sclerotic border and more cortical expansion on radiographs. On microscopic evaluation, moreover, they show whirling of fibrous tissue generally without chondroid or myxoid tissue.

Enchondroma

On radiographs, these lesions are typically central rather than eccentric but also may have associated lucent areas. Mineralization of the hyaline cartilage is generally much more extensive in mature enchondromas than in CMFs. Histologically, enchondromas are made up of almost purely chondroid tissue with a bland-looking histologic appearance and no atypical cells or myxoid background. Patients with enchondroma are typically older than are patients with CMF.

Unicameral bone cyst

These lesions have a central location and demonstrate absence of cartilage mineralization. They are cystic structures with hemosiderin-laden macrophages, straw-colored fluid, and a thin, fibrous lining.

Giant cell tumor of bone

Patients with giant cell tumor (GCT) of bone are typically older than persons with CMF, and the radiographic and cellular features of GCT differ from those of CMF. GCTs, while having a metaphyseal origin, typically extend to involve the epiphysis. They can also have prominent extraosseous extension. The defining histologic characteristic of GCT is the presence of a plethora of multinucleated giant cells, with the background cells containing nuclei that are similar to those in the giant cells.¹⁵

Aneurysmal bone cyst

Although the age range for aneurysmal bone cyst (ABC) and CMF is similar, the former typically demonstrates marked, ballooning cortical expansion and septations radiographically. Histologically, an ABC is made up of large, blood-filled vascular spaces and a highly vascular stroma with multinucleated giant cells, hemosiderin deposition, and histiocytes.

See also the following topics in eMedicine:
Aneurysmal Bone Cyst [Orthopedic Surgery]
Aneurysmal Bone Cyst [Radiology]
Enchondroma and Enchondromatosis
Fibrous Cortical Defect and Nonossifying Fibroma
Giant Cell Tumor [Orthopedic Surgery]
Giant Cell Tumor [Radiology]
Unicameral Bone Cyst

Workup

Laboratory Studies

• CMF does not cause any laboratory abnormalities.

Imaging Studies

• Radiographs^16,17
  • CMFs are well-defined, eccentric, elongated, radiolucent lesions that usually occur in the metaphysis of long bones. A diagnostic feature, when present, is a nearly hemispherical "bite" from the cortical margin without periosteal reaction. The greatest dimension of CMFs is typically 1-10 cm. The margins are often sclerotic with scalloped borders and may demonstrate mild cortical expansion. The lesions can extend into the diaphysis or epiphysis but do not cross the open physeal plate.
  • Trabeculations within the tumor, which reflect bony ridges formed around a lobulated tumor periphery, may be visible on radiographs.
  • Matrix calcifications are unusual, appearing in only 2-13% of lesions.¹⁸
  • When CMF involves the vertebrae (in approximately 8% of cases), radiographs may reveal a more aggressive appearance, with cortical destruction and extension into soft tissue.¹⁹
  • Lesions of the small bones of the hands or feet are more typically central and expansile.
  • CMFs may have associated secondary ABCs, visible on radiographs.
• Computed tomography (CT) scans
  • Mild cortical expansion may be observed on CT scans, and the lesions have a density greater than fluid throughout, except in areas affected by a secondary ABC.
  • CT scans can also reveal the characteristic lack of mineralization within the lesions.
• Magnetic resonance imaging (MRI) scans
  • The chondroid and myxoid tissues, as well as any normal hyaline cartilage within the lesion, have an intermediate to high signal on proton-density and T2-weighted images and have a low signal on T1-weighted images. The fibrous tissue components have a variable appearance, depending on their vascularity.
  • Because of their diverse tissue components, CMFs have a heterogeneous appearance. They are typically solid but can have cystic areas as well.
  • Secondary ABCs have typical septations and, in many cases, fluid-fluid levels reflecting the blood-filled vascular channels. MRI scans may demonstrate soft-tissue or bone marrow edema extending well beyond the lesion and are helpful in preoperative planning.
• Bone scans - CMFs usually have increased activity on bone scintigraphy.

Procedures

• Biopsy is used for histologic examination. A generous tissue sample is required for an accurate diagnosis, because small biopsies may not be representative.

Histologic Findings

Microscopically, CMFs are lobulated or pseudolobulated, with peripheral condensation of more cellular tissue within the lobules. Composed of myxoid or chondroid tissue, the center of each lobule is hypocellular. The surrounding stroma is denser, with spindle-shaped cells, blood vessels, and occasional multinucleate giant cells. Tumor nuclei may be hyperchromatic, are of moderate size, and may lie in chondroid lacunae. Nuclear atypia can be observed, but mitoses are rare or absent. Microcalcification is present in 15-20% of cases, with an increased incidence in older patients.

Scattered areas of hyalinization, xanthomatous changes, cholesterol clefts, and cystic degeneration may be noted, including secondary ABCs. The tumors have a heterogeneous immunohistochemical staining pattern, with the central chondroid areas staining positively for S-100 protein and the peripheral, hypercellular tissue staining diffusely for muscle and smooth muscle actin.²⁰ None of the cells express desmin.

Staging

Local staging typically includes plain radiographs and an MRI or CT scan. Because CMF does not metastasize, there is no need for routine chest radiographs or other systemic staging studies. A total skeletal bone scan is generally advisable during the initial evaluation to assess local activity and to ensure the solitary nature of the tumor.

• Search for CME/CE on This Topic »

• Chondromyxoid Fibroma (Radiology)
• Benign Skull Tumors (Neurology)
• Aneurysmal Bone Cyst (Radiology)

• Giant Cell Tumor