History
The challenge is to differentiate the varying types of bone tumors. Imaging studies and the appearance of the lesion are the primary differentiating factors. The location of the lesion is of little differential diagnostic value, although lesions of developmental origin have a strong midline propensity.
Single, small, grossly round and oval lesions are more likely to be benign. The presence of peripheral sclerosis strongly favors a benign tumor. The margin of a lesion is of no diagnostic value.
Intralesional calcifications are more common in benign tumors. Peripheral bone vascularity also indicates a benign process.
The differential diagnosis includes encephalocele, meningoencephalocele, venous lakes of the skull, pacchionian depression, fractures, surgical defects, osteomyelitis, tuberculosis, syphilis, osteoporosis, and congenital hemolytic anemia.
The following tumors manifest as slow-growing painless masses: osteoma, ossifying fibroma, chondroma, nonossifying fibroma, xanthoma, hemangioma, epidermoid, dermoid, meningioma, and fibrous dysplasia.
Other tumors include osteoid osteoma, osteoblastoma, chondroblastoma, [6] chondromyxoid fibroma, desmoplastic fibroma, giant cell granuloma, eosinophilic granuloma, and aneurysmal bone cyst.
Associated headache is nonspecific in nature.
Lymphangioma manifests as a painless cystic defect.
Osteoid osteoma manifests with nocturnal local tenderness that is relieved by aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs).
Cranial nerve deficits are observed in chondroblastoma, giant cell granuloma, epidermoid, dermoid, fibrous dysplasia, and Paget disease.
A rapidly growing mass is observed in desmoplastic fibroma and giant cell granuloma.
Tumor location is unreliable for diagnosis. However, certain tumors appear at the convexity more than the skull base and vice versa.
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Osteomas usually involve the frontal bone.
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Ossifying fibromas favor the frontotemporal region.
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Cartilage tumors involve the skull base.
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Giant cell granuloma affects the sphenoid, temporal, and ethmoid areas.
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Eosinophilic granuloma affects the frontoparietal area.
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The globular variety of hemangiomas affects the skull base, and the sessile type affects the frontotemporal region.
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Epidermoids and dermoids usually involve the cerebellopontine angle, parapituitary region, and calvaria. Dermoids prefer the midline.
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Ossifying meningiomas involve the frontal parietal area.
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Paget disease usually involves the skull base.
Physical
Physical findings vary according to tumor type.
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The lesion may be tender or nontender.
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It may be soft or hard.
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Cranial nerve deficits (eg, diplopia, hearing loss, vertigo, sensation loss) may be seen.
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Other neurological deficits may be noticed depending on the nature, size, extent, and location of the lesion
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Orbital tumors arise from the orbital walls and are a relatively distinct set of tumors that may present with diplopia and or declining vision
Causes
Benign skull tumors are sporadic in occurrence. However, specific syndromes involving skull tumors have been described.
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Gardner syndrome is the triad of the following:
Multiple osteomas of the skull, sinus, and mandible
Soft tissue tumors of skin
Colon polyps
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McCune-Albright syndrome comprises the triad of the following:
Polyostotic fibrous dysplasia
Hyperpigmented skin macules
Precocious puberty
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Hand-Schüller-Christian disease consists of the following:
Diabetes insipidus
Exophthalmos
Bone lesions
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Multiple enchondromas is known as Ollier syndrome.
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Maffucci syndrome consists of the following:
Enchondromas
Dyschondroplasia
Cavernous hemangiomas of soft tissues or viscera
Complications
Complications of nontreatment vary based on the nature, size, extent, and location of the tumor.
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Composite CT scan, MRI, and angiogram of a symptomatic ossifying fibroma with extensive involvement of the skull base in a 12-year-old girl whose primary symptom was exophthalmos and loss of vision bilaterally.
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Lateral skull radiograph of a 73-year-old patient with a slow-growing, nontender skull lesion. Note the typical honeycomb appearance.
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Head CT scan of a 73-year-old patient with a slow-growing, nontender skull lesion shows a well-defined nonenhancing lytic lesion with calcification and honeycomb appearance.
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Sagittal magnetic resonance imaging (MRI) section of the brain of a 73-year-old patient with a slow-growing, nontender skull lesion showing a nonenhancing soft tissue mass. This lesion proved to be a hemangioma.
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Lateral skull radiograph of a 17-year-old adolescent male with a painless slow-growing mass. The single round lytic lesion was found to be an epidermoid.
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Fibrous dysplasia involving the sphenoid sinus and pterygoid plates as well as the sella. This is an asymptomatic lesion; observation was recommended.
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Head CT scan of a 78-year-old woman with Paget disease. Note the cotton wool appearance of the lesion, with varying degrees of bone formation and no clear edges. Observation was recommended.
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A well-preserved 90-year-old female patient with a mass in the occiput with an inability to sleep and rapid atrial fibrillation related to hyperthyroidism due to a solitary thyroid metastasis. This sagittal CT scan demonstrates a lytic lesion.
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Same patient as above with mixed attenuation calvarial and epidural mass on MRI; lesion was resected.
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A 49-year-old male patient with occipital headache and no deficits. A CT scan demonstrates an expansile lesion involving the diploe. This was demonstrated to be a dermoid tumor at histopathology.
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Same patient as above with an expansile lesion involving the diploe on MRI.
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A 56-year-old female patient with a small bump on her forehead which slowly increased in size over a 5-year period. A CT scan revealed a lesion which was resected with endoscopic assistance so the incision would be in the hairline. Histopathological examination confirmed an osteoid osteoma.
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Axial and coronal CT scan images of a 40-year-old female patient with progressive visual decline in the left eye for >2 years. Patient was blind at presentation. A cranial resection was done with resulting return of light perception. Histopathological examination confirmed an intraosseous meningioma.
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Coronal T1 and axial T2 images for same patient as above.
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MRI images of a 40-year-old patient with a visual field defect in the left temporal (Ollier disease). Both lesions were resected and shown to be osteochondromas on histopathological examination.
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CT scan images for same patient as above.
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Axial and coronal T1 MRI images of a 65-year-old patient with a chronically large jaw who presented with h/a and left visual worsening due to fibrous dysplasia. Transnasal surgery combined with an eyelid approach was completed to open up the frontal sinus ostium and decompress the orbit.
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Coronal and sagittal CT bone window images of same patient as above.
