British Journal of Radiology 75 (2002),931-932 © 2002 The British Institute of Radiology
A lump in the head
S S Badr, FFR, RCSI
1
M H Dahniya, FRCR
1 and
K C Katchy, MRCPath, FRCPC
2
Departments of 1 Diagnostic Radiology and Imaging and 2 Pathology, Al-Sabah Hospital, Kuwait
Correspondence: Dr M H Dahniya, P.O. Box 31162, 90802 Sulaibikhat, Kuwait
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Introduction
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A 31-year-old male presented to the casualty department with a history of severe intermittent headaches for 3 months, vomiting for 2 months and recent loss of concentration. For the past 10 years, he had been aware of a hard, slow growing swelling on the right side of his head, but had sought no medical advice because the mass was causing no symptoms. He had no other relevant clinical history. On physical examination there was a large, stony, hard, non-tender swelling on the right side of the head. Apart from the cranial mass, physical examination was normal. Routine laboratory investigations, including serum calcium and phosphate, alkaline phosphatase and creatinine, were normal. Plain skull radiographs were obtained (Figure 1
). What is your differential diagnosis at this stage? Further radiological investigations included radionuclide bone scanning, which showed marked increase of tracer uptake by the mass CT (Figure 2) and MRI (Figure 3). What is the final diagnosis?
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Answer
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The plain skull radiographs revealed a large bony mass in the right frontoparietal region (Figure 1
). CT demonstrated a large enostotic component to the mass, causing brain and ventricular compression and shift of midline structures (Figure 2). The tumour showed mixed signal intensity on both T1 and T2 weighted sequences. On T1 imaging, most of the mass was of low signal intensity but the central portion was of intermediate signal intensity with irregular scattered foci of high signal (Figure 3a). On T2 imaging, the tumour was predominantly of high signal intensity with a low signal periphery and septations (Figure 3b). The signal changes were interpreted as probably representing recent haemorrhage within the tumour. The radiological diagnosis was either a giant osteoma or fibrous dysplasia. The tumour was excised without complications and histology showed compact trabeculae of lamellar bone with a variable amount of osteoid and prominent cement lines consistent with osteoma. The tumour was successfully excised, the patient remaining well and symptom free.
Osteomas are benign, slow growing tumours consisting entirely of well differentiated bone and occur almost exclusively in the craniofacial region [1]. They are of two types: dense or ivory, and trabeculated or spongy, the latter occurring more commonly in the cranial vault [1]. Haddad et al [2] have recently classified cranial osteomas into four types: intraparenchymal; dural; skull base; and skull vault. Intraparenchymal osteomas have no connection to dura or bone, are the rarest type [3] and may be confused with intracranial calcifications. Dural osteomas have no bony attachment, arise mainly from the falx, are asymptomatic and are often incidental findings on plain radiographs. Skull base osteomas are most common in the frontal sinus, but may also occur in the ethmoid air cells, maxillary and sphenoid sinuses, the maxilla and mandible [4] and occasionally arise in the temporal bone [4]. They are rarely symptomatic but may be the cause of headaches, orbital invasion and deformity, pneumocephalus, rhinorroea, meningitis and abscess. Skull vault osteomas may arise from the outer table (exostotic) or inner table (enostotic), and are usually asymptomatic. The enostotic form may produce raised intracranial pressure, as in our patient, or other symptoms similar to those of a meningioma [1]. Familial osteomas of the cranial vault and the middle ear have been reported.
Giant cranial vault osteomas of the type reported here are rare and the symptomatic form is even rarer. They have been reported in association with Gardner's syndrome [4, 5] and with acromegaly and hydrocephalus [6]. In the latter, the acromegaly was said to have favoured the marked growth of the osteoma, and the hydrocephalus was the result of superior sagittal sinus compression by the osteoma and alteration in cerebrospinal fluid resorption. Our patient's giant vault osteoma had both enostotic and exostotic components, the enostotic component being responsible for the patient's symptoms of raised intracranial pressure.
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Footnotes
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Current address for S S Badr: Department of Radiology, Hamad General Hosptial, Doha, Qatar. 
Received for publication April 11, 2001.
Revision received May 29, 2001.
Accepted for publication June 19, 2001.
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References
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- Watt I, Cobby M. Tumors and tumor like conditions of bone (1). In: Sutton D, editor. Textbook of Radiology and Imaging. London: Churchill Livingstone, 1998:136.
- Haddad FS, Haddad GF, Zaatari G. Cranial osteomas: their classification and management. Report on a giant osteoma and review of the literature. Surg Neurol 1997;48:143–7.[Medline]
- Lee ST, Lui TN. Intracerebral osteoma: case report. Br J Neurosurg 1997;11:250–2.[Medline]
- Havos AG. Osteoma and Gardner's syndrome. In: Havos AG, editor. Bone tumors: Philadelphia, PA: WB Saunders Co, 1991:1–7.
- Noterman J, Massager N, Vloeberghs M, Brotchi J. Monstrous skull osteomas in a probable Gardner's syndrome: a case report. Surg Neurol 1998;49:302–5.[Medline]
- Corriero G, Maiuri F, Giamundo A, et al. Giant osteoma of the cranial vault with acromegaly and hydrocephalus. A case report. J Neurosurg Sci 1985;29:331–4.[Medline]
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Introduction
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