DOI:10.2214/AJR.07.7029
AJR 2007; 189:S61-S63
© American Roentgen Ray Society
AJR Teaching File: Nuclear Imaging of a Tender Skull Mass
Ba D. Nguyen1 and
Dean McNaughton
1 Both authors: Department of Radiology, Mayo Clinic, 13400 E Shea Blvd.,
Scottsdale, AZ 85255.
Received January 27, 2006;
accepted after revision April 10, 2006.
Address correspondence to B. D. Nguyen
(nguyen.ba{at}mayo.edu).
Keywords: head and neck imaging • hemangioma • MRI • nuclear medicine
Clinical History
A 69-year-old woman presents with a tender left skull mass. A spiculated
left upper lung mass is seen on chest radiography.
Radiologic Description
Technetium-99m MDP (methylene diphosphonate) whole-body bone scintigraphy
shows two areas of abnormal radiotracer uptake in the left parietal bone and
the supraorbital aspect of the right frontal bone; these findings are
confirmed by lateral spot views (Figs.
1A and
1B). Axial T2-weighted MR
images show increased signal intensity in the diploic locations of the right
frontal and left parietal regions (Fig.
1C). On T1-weighted MR images, these calvarial lesions exhibit
isointense signal to the brain and enhance with contrast (Figs.
1D and
1E).
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Fig. 1A —69-year-old woman with tender left calvarial mass and
spiculated left upper lung tumor. Anterior and posterior whole-body bone
scintigrams show two abnormal foci of radiotracer accumulation at supraorbital
aspect of right frontal bone and left parietal bone (arrows).
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Fig. 1B —69-year-old woman with tender left calvarial mass and
spiculated left upper lung tumor. Lateral spot views of skull confirm right
frontal (right) and left parietal (left) calvarial lesions
(arrows).
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Fig. 1C —69-year-old woman with tender left calvarial mass and
spiculated left upper lung tumor. Axial T2-weighted images show increased
signal intensity of right frontal and left parietal lesions with their diploic
location (arrows).
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Fig. 1D —69-year-old woman with tender left calvarial mass and
spiculated left upper lung tumor. Axial T1-weighted images show right frontal
and left parietal calvarial tumors with isointense signal to brain
(arrows).
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Fig. 1E —69-year-old woman with tender left calvarial mass and
spiculated left upper lung tumor. Contrast-enhanced axial T1-weighted images
show enhancement of right frontal and left parietal lesions
(arrows).
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Differential Diagnosis
The differential diagnosis for a tender skull mass and a spiculated left
upper lung mass includes calvarial metastasis, meningioma, Paget's disease,
and calvarial cavernous hemangioma.
Diagnosis
The diagnosis is calvarial cavernous hemangioma.
Commentary
In the clinical context of lung malignancy, calvarial metastases are highly
ranked in the differential diagnosis of this case presentation. Metastases
usually exhibit aggressive MR features with ill-defined margins in the
calvarial diploe, multiple lesions, erosion or invasion of the inner and outer
tables, and associated focal meningeal contrast enhancement from dissemination
[1]. None of those MR features
were noted in this patient. Meningiomas are usually intracranial and
extraaxial in location and are therefore easy to distinguish from intradiploic
lesions. Rare intraosseous meningiomas, also known as primary extradural
meningiomas, represent only 1–2% of all lesions of this group and may be
difficult to distinguish from calvarial hemangiomas solely on the basis of
location. The usually hypo- to isointense T1 and iso- to hyperintense T2
signals of meningiomas may help to differentiate these two uncommon entities
[2]. Paget's disease is
characterized by disorganized osseous enlargement and calvarial thickening
with variable degrees of marrow MR signal intensity, depending on whether the
disease is in the active (heterogeneous signals), mixed (heterogeneous
signals), or blastic inactive (low signals) phase
[3]. The diploic frontal and
parietal locations, the lack of obvious disruption of inner and outer tables
of the skull, and the T1 and T2 signal intensities of the lesions suggests the
diagnosis of calvarial cavernous hemangiomas.
Surgical resection with pathologic evaluation of the left parietal lesion
was consistent with a diagnosis of cavernous hemangioma. A subsequent
18F-FDG PET evaluation and staging of the left upper lung
adenocarcinoma showed no radiotracer uptake of the right frontal bone lesion,
which was suggestive of a hypometabolic process. The benign behavior of this
lesion was further confirmed by its stability during the 4-year imaging
follow-up.
Cavernous hemangiomas of the skull are rare entities arising from the
diploe on the frontal and parietal bones. When they coexist with a primary
lung malignancy, they mimic calvarial metastases, especially with clinical
manifestations of mass and tenderness.
Osseous hemangiomas are relatively uncommon benign vascular tumors,
predominantly seen in patients in their fourth and fifth decades
[4]. The female-to-male ratio
ranges from 2:1 to 3:1. Osseous hemangiomas account for 0.7–1% of all
bone tumors [5]. They are
usually encountered in the vertebrae and detected as incidental findings
during cross-sectional imaging of the spine
[6]. Calvarial hemangiomas are
rare, with an incidence of 0.2% of all osseous neoplasms and with a preference
for frontal and parietal locations
[7]. Calvarial hemangiomas are
of the cavernous type; vertebral counterparts are of the capillary type
[5]. Multiple hemangiomas of
the skull have been reported with a frequency of 15% of all identified
calvarial hemangiomas [6].
Calvarial hemangiomas are slow-growing tumors that are only symptomatic when
they become large or compress adjacent neurologic structures
[5]. Calvarial hemangiomas
develop in the diploic space constituted by dilated blood vessels with fibrous
septa. Their vascular supply is frequently from the middle meningeal artery
and branches of the external carotid artery. Unlike the characteristic
"corduroy" radiographic pattern and "polka dot" CT
appearance of vertebral hemangiomas, a calvarial hemangioma may appear as a
lytic expansile and "bubbly" lesion with a sclerotic rim or a
spiculated "sunburst" skull tumor
[4]. CT is helpful in
delineating the osseous extension to adjacent skull structures and possible
complications such as inner or outer table bone fracture
[5]. Depending on their
composition, calvarial hemangiomas may exhibit a variable range of MR signal
intensities on T1-weighted images (mostly isointense or hyperintense to the
brain) and appear hyperintense on T2-weighted images. Because of their
vascular nature, calvarial hemangiomas show IV contrast enhancement on CT and
MRI [6]. Osseous hemangiomas
frequently exhibit increased 99mTc MDP up-take
[8].
Objective
The educational objective of this article is to teach the epidemiology,
imaging features, and differential diagnosis of calvarial cavernous
hemangioma.
Conclusion
Knowledge of the location and MRI features of calvarial hemangiomas can
distinguish this lesion from other benign and malignant tumors involving the
skull.
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Clinical History
Radiologic Description
