<unk>  is the common name for primitive neuroectodermal tumor.<unk>  is the second most common malignant bone tumor in patients younger than 20 years.<unk>  is a small round-cell tumor in which cancer cells are found in the bone or in soft tissue.<unk>  may occur anywhere in the body, but most commonly occurs in the pelvis and proximal long tubular bones.  The pathogenesis of<unk>  includes a t(11;22) chromosomal translocation. On microscopic histopathological analysis, presence of small round cells that have a high nuclear to cytoplasmic ratio, vacuolated cytoplasm, and faded boundaries are characteristic findings of<unk> . There are no<unk> tablished causes for<unk> . The most common symptoms of<unk>  include localized bone pain, swelling, fever, loss of appetite, and weight loss. On x-ray,<unk>  is characterized by permeative lytic lesion, periosteal reaction, and soft tissue calcification. On MRI,<unk>  is characterized by low to intermediate signal on T1, heterogenously high signal intensity on T2, and heterogenous but prominent enhancement on T1 contrast.
Ewing's sarcoma
Osteoblastoma
Synovial sarcoma
Kaposi's sarcoma
Malignant fibrous histiocytoma
Osteosarcoma
Chondrosarcoma
Osteochondroma