Primary Malignant Skull Tumors Workup

Updated: Aug 09, 2017
  • Author: Draga Jichici, MD, FRCP, FAHA; Chief Editor: Tarakad S Ramachandran, MBBS, MBA, MPH, FAAN, FACP, FAHA, FRCP, FRCPC, FRS, LRCP, MRCP, MRCS  more...
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Workup

Laboratory Studies

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  • Anemia, an elevated white blood count (WBC), and reduced platelets are characteristic of malignancies involving the bone marrow.

  • Immunoglobulins (eg, IgG, IgA, IgM, IgD) are elevated in multiple myeloma.

  • Protein M can be found in the urine and serum in myeloma.

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Imaging Studies

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  • Plain skull x-ray film and head CT scan

    • Most of the malignant skull tumors appear as radiolucent lesions, single or multiple, with irregular borders and no periosteal reaction.

    • Osteosarcomas appear as osteolytic soft-tissue extensions. They may have calcification within the lesion, no periosteal reaction, and poorly defined margins. The typical (but not frequent) appearance is the sun-ray picture.

    • Chondrosarcomas have no reliable radiological features and are characterized by lytic and sclerotic changes within poorly defined margins.

    • Fibrosarcomas are radiolucent lytic lesions with thinning and widening of the cortex, minimal periosteal involvement, and irregular margins.

    • Ewing sarcoma has a typical onion skin appearance with laminated periosteal changes. On CT scan, it appears as an isodense mass surrounded by a hypodense area and hyperostosis. It is also contrast enhancing.

    • Angiosarcomas are destructive lesions with cortical erosion and reactive ossification. On CT scan, they show heterogeneous enhancement with focal necrosis.

    • Plasmocytomas/multiple myelomas usually present as multiple lytic lesions that involve both the inner and outer tables, as well as the diploë from which they arise. On CT scan, depicted below, they are hyperdense, homogeneous enhancing lesions.

      Head CT scan of a 60-year-old man with a history o Head CT scan of a 60-year-old man with a history of multiple myeloma for 2 years, showing multiple lytic lesions that involve both the inner and outer tables as well as the diploë.
    • Chordomas are soft-tissue masses usually seen in the nasopharyngeal area with various degrees of calcification. CT scan shows a soft-tissue mass with extensive bone destruction.

    • Metastatic neoplasms can be either of the following:

      • Osteoblastic, with sclerosis and thickening (eg, prostate, breast, bladder, hypernephroma)

      • Osteoclastic, with bone destruction and lucency (eg, lung, uterus, GI tract, thyroid, melanoma, neuroblastoma)

    • Giant cell tumors usually involve the sphenoid bone and commonly erode the sellar region. On brain CT scan, giant cell tumors are hyperdense, contrast-enhancing masses.

  • MRI

    • Most tumors are hypointense on T1-weighted images and hyperintense with heterogeneous signal on T2-weighted images.

    • Enhancement is common.

  • Bone scan: 99m technetium scan shows all malignant processes as hot areas.

  • Arteriogram: Tumors of vessel origin or associated with multiple myeloma have a high degree of vascularity.

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Other Tests

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  • Bone marrow biopsy

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Procedures

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  • Biopsy of the lesion is crucial for establishing the diagnosis and deciding on treatment options.

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Histologic Findings

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  • Osteosarcomas are composed of a malignant spindle cell stroma, which directly produces osteoid or immature bone (osteoblastic, chondroblastic, or fibroplastic form). [9]

  • Low-grade chondrosarcomas (myxochondrosarcoma) are characterized by chondroid and immature cartilage deposition in areas of myxomatous change and cystic degeneration. The high-grade type (mesenchymal chondrosarcoma) is characterized by the absence of cartilage lobules and the presence of fibrosarcomatous areas. Groups of chondromatous cells lose their usual lobulation and begin to spindle out. Both types are vimentin positive.

  • Fibrosarcoma is characterized by varying amounts of collagen production and the absence of bone, osteoid, or cartilage. The medullary subtype has a better prognosis than the periosteal subtype.

  • Giant cell tumor (osteoclastoma) consists of a well-vascularized tissue mass of plump, spindle, or ovoid stroma cells together with uniformly dispersed, numerous, large, multinucleated giant cells.

  • Ewing sarcoma appears as uniform, densely packed small cells with indistinct cytoplasmic borders and many mitotic figures. They stain strongly with periodic acid-Schiff (PAS). [3]

  • Angiosarcomas (hemangiopericytoma or hemangioendothelioma) are characterized by the formation of irregular anastomosing vascular channels lined by one or more layers of atypical endothelial cells and pericytes, which have an anaplastic immature appearance.

  • Multiple myeloma is characterized by widespread osteolytic bone destruction by dense tumor cells that look like plasma cells clustered in close aggregates. [10]

  • Chordomas consist of physaliphorous cells (large, vacuolated, mucus containing) with a lobular arrangement and abundant extracellular mucoid tissue.

  • Metastatic tumors have the same or similar histologic features as their primary tumors.

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