Imaging studies A variety of imaging studies can be used to diagnose<unk> , with radiographs being the most common. Laboratory studies are not considered useful. Classical<unk>  (appearing on long bones) appears as a well-defined eccentric oval or round lytic lesion that usually involves the adjacent bone cortex without periosteal reaction. A sclerotic margin can be seen in some cases. For long bone<unk> s the tumor is typically contained to the epiphysis or apophysis but may extend through the epiphyseal plate.<unk> s are usually located in the medullary portion of bones and can, in some cases, include the metaphysis. However, true metaphyseal<unk> s are rare and are typically the result of an extension from a neighboring epiphyseal legion. Most lesions are less than 4 cm. A mottled appearance on the radiograph is not atypical and indicates areas of calcification which is commonly associated with skeletally immature patients. Additionally, one-third of all cases involve aneurysmal bone cysts which are thought to be the result of stress, trauma or hemorrhage. In cases involving older patients or flat bones, typical radiographic presentation is not as common and may mimic aggressive processes. Other imaging techniques involve computed tomography (CT), magnetic resonance imaging (MRI), and bone scans, which may be helpful in determining the anatomical boundaries, associated edema, or biological activity of the<unk> , respectively. MRI studies may show extensive oedema around the lesion and show variable T2 signal intensity. Histological findings Chondroid differentiation is a common feature of<unk> . A typical histological appearance consists of a combination of oval mononuclear and multi-nucleated osteoclast-type giant cells. However this is not a prerequisite for diagnosis, as cells with epithelioid characteristics have been observed in lesions of the skull and facial bones. A "chicken-wire" appearance is characteristic of<unk>  cells and is the result of dystrophic calcification that may surround individual cells. Although, calcification may not be present and is not a prerequisite for diagnosis. Mitotic figures can be observed in<unk>  tissue but are not considered atypical in nature, and therefore, should not be viewed as a sign of a more serious pathology. There is no correlation between mitotic activity and location of the lesion. Furthermore, the presence of atypical cells is rare and is not associated with malignant<unk> . There are no discernible histological differences observed when comparing the aggressive form of<unk>  that can cause recurrence or metastases with its less aggressive, benign, counterpart. Differential diagnosis Chondromyxoid fibromas can share characteristics with<unk> s with regards to histologic and radiographic findings. However they more commonly originate from the metaphysis, lack calcification and have a different histologic organization pattern. Other differential diagnoses for<unk>  consist of giant cell tumors, bone cysts, eosinophilic granulomas, clear cell chondrosarcomas, and enchondromas (this list is not exhaustive).
Chondroblastoma
Mycetoma
Esthesioneuroblastoma
Ganglioneuroblastoma
Myelolipoma
Lipoblastoma
Myxoid cyst
Brown tumor