Chondromyxoid Fibroma Differential Diagnoses

Updated: Sep 16, 2020
  • Author: Stefanos F Haddad, MD; Chief Editor: Omohodion (Odion) Binitie, MD  more...
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DDx

Diagnostic Considerations

Chondrosarcoma (conventional)

Chondrosarcoma of low grade may mimic chondromyxoid fibroma (CMF) histologically, except for the lack of a myxoid element. It typically has distinguishing demographic and radiographic characteristics. The peak incidence of chondrosarcoma occurs in the sixth and seventh decades of life, whereas CMF develops in the second and third decades.

Radiographically, chondrosarcoma tends to be central and have abundant calcifications. Chondrosarcoma and CMF, however, may each have mild expansion of cortical bone. In higher grade or long-standing chondrosarcoma, cortical erosion and a soft-tissue mass may be observed. [21, 22]

The histopathologic features of CMF—including a lobular growth pattern, focal deposits of hyaline cartilage, rare mitotic figures, and even cellular pleomorphism—may be similar to those of chondrosarcoma. However, mucinous material, nuclear atypia, and multiple pleomorphic or multinuclear cartilage cells all suggest chondrosarcoma. In addition, chondrosarcoma tends to behave in a more malignant fashion. A myxoid element is not found in chondrosarcoma.

Chondroblastoma

Chondroblastoma and CMF occur in individuals of the same age group and may have similar histologic features, including chondroblastic differentiation, giant cells, and a markedly positive S-100 stain result. Like chondrosarcomas, chondroblastomas lack a myxoid element.

Several features of chondroblastoma differ from those of CMF. Chondroblastomas typically occurs in an epiphyseal location, whereas CMFs are 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. [23]

Nonossifying fibroma

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

Enchondroma

On radiographs, these lucent lesions are typically central rather than eccentric and do not bulge or break the cortex. Mineralization of the hyaline cartilage is generally 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 fibrous or myxoid element is present. Patients with enchondroma are typically older than are patients with CMF. Enchondromas are most common in the hand.

Unicameral bone cyst

These lesions have a more central location and demonstrate absence of cartilage. They are cystic structures with hemosiderin-laden macrophages, straw-colored fluid, and a thin, fibrous lining. Occasionally, unicameral bone cysts can have a radiographic appearance similar to that of CMFs; otherwise, they are easily differentiated.

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, though of metaphyseal origin, can extend into the epiphysis. The defining histologic characteristic of GCT is the presence of a plethora of multinucleated giant cells. [24] CMFs contain fewer giant cells located near the periphery. GCTs have no myxoid or chondroid elements.

Aneurysmal bone cyst

Although the age range for aneurysmal bone cyst (ABC) and CMF is similar, the former typically demonstrates ballooning cortical expansion. 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. Both lesions can expand the cortex, but they are easily differentiated radiographically and histologically. The development of a secondary associated ABC within a CMF has been reported.

Differential Diagnoses