| 〔Case Report〕 |
| Changes of magnetic resonance images during treatment of orbital pseudotumor |
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| Katsuhiro Hanawa 1), Emiko Adachi-Usami 1), Hiroshi Nagata 2) and Atsushi Mizota 3) |
| （Received September 22, 2005, Accepted September 28, 2005） |
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SUMMARY
| A 61-year-old woman presented with sudden headache and deep ocular pain on the right side. She had an episode of fever up to 39 ℃ about 1 week before her initial visit. The ocular pain was temporary, but soon after that, ptosis and a swelling of the lid developed in the right eye. She did not report tinnitus. The proptosis was 21 mm in the right eye. T2-MR imaging showed a diffuse, high density mass in the orbit, but the muscles and optic nerve on the right side were normal. A tentative diagnosis of orbital pseudotumor was made, oral predonisolone was prescribed. The follow-up MR images demonstrated a slow but certain recovery of the clinical signs. |
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Key Words
| MR imaging, Orbital pseudotumor, steroid therapy |
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Ⅰ．Introduction
Orbital pseudotumors are diagnosed by the exclusion of neoplastic, infectious,
or systemic inflammatory or immunologic causes. Accordingly, a number of
clinical and laboratory tests are necessary to obtain a decisive diagnosis.
Among these tests, imaging techniques such as X-ray computed tomography
（CT）［1-4］and magnetic resonance imaging （MRI） are very helpful［4-8］.
We report a case of orbital pseudotumor that responded to steroid therapy,
and the follow-up MR images demonstrated a slow but certain recovery of
the clinical signs.
Ⅱ．Case report
A 61-year-old woman suddenly developed headache and deep ocular pain
on the right side on June 14, 2003 and her body temperature was 39 ℃.
The ocular pain was temporary, but soon after that, ptosis and a swelling
of the lid developed in the right eye. She did not report tinnitus.
She was referred to our clinic on June 23, 2003. Informed consent was obtained from the patient.Her corrected visual acuity at the initial visit was 20/25 in the right eye, and 20/20 in the left. The pupils were isocoric, and relative afferent pupillary defects were not detected. The proptosis was 21 mm in the right and 15 mm in the left eye, but no tumor was palpable. Hess chart test showed severe limitation to upper and lateral gaze. The visual fields by Goldmann perimetry and Humphrey automated perimetry were full.
T2-weighted MRI （T2-MRI） on June 23 showed a diffuse, high density mass in the right orbit, but the muscles and optic nerve on the right side were normal （Fig. 1）. Gadolinium enhanced MRI on the same day demonstrated very high density
mass in the right orbit （Fig. 2A）. No systemic diseases were found. These findings allowed us to exclude
orbital neoplasms, myositis, and thyroid ophthalmopathy. A tentative diagnosis
of orbital pseudotumor was made, and 30 mg/day predonisolone was prescribed
on June 24.
T2-MRI on June 27 demonstrated high density mass in the right orbit （Fig.3A）, although her ptosis and proptosis had improved and the Hess chart findings
were almost normal. On July 4, the ptosis and proptosis were completely
resolved, and predonisolone was gradually reduced and stopped completely
on August 10. T2-MRI of July 18 showed decreased signal density, but it
was still higher than in the left （Fig. 3B）.
Although her symptoms were completely recovered, the T2-MRI on September
9 （Fig. 3C） demonstrated high density signals in the orbit. But the density was
considerably reduced compared with MRI at the first visit. Enhanced MR
imaging on September 9 （Fig. 2B） showed enhancezment in right orbit. On January 20, 2004, the MRI signals
in the right orbit were the same as that in the non-affected eye （Fig. 3D） and enhanced MRI showed no enhancement in her right orbit （Fig. 2C）. |
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| Fig. 1 T2-MR imaging on June 23, 2003 showed a diffuse, high density mass in the right orbit （arrow）. |
Fig. 2 Follow-up T1 with Gadolinium enhancement with fat-saturation on June 23 （A）, September 9 （B）, 2003 and January 20（C）, 2004. These images show a marked enhancement of the inflammatory tissue of the right orbit, and it reduced following steroid therapy. But there is some subclinical signs of inflammation when the symptoms are gone （September 9） |
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| Fig. 3 T2-weighted MR images with fat-saturation on June 27 （A）, July 18 （B）, September 9 （C）, 2003 and January 20 （D）, 2004. Signal intensity of the right orbit decreased following steroid therapy. |
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Ⅲ．Discussion
Orbital pseudotumors are idiopathic, nonspecific orbital inflammatory
masses. They are associated with moderate to severe pain, eyelid and conjunctival
swelling, and protrusion of the globe. The CT and MRI in pseudotumors are
characterized by inflammatory changes in orbital structures, such as muscles,
fat, lacrimal glands, orbital apex, and Tenon’s capsules. These findings
lead to a diagnosis of an orbital pseudotumor in most cases［1-8］.
On MRI, the pseudotumor infiltrates have low signal intensities on T1-weighted
images and an increased signal density on T2-MRI. However, it is often
difficult to differentiate a pseudotumor from lymphoproliterative diseases,
when there is diffuse infiltration into the entire orbital space as is
observed in lymphoproliferative disease［4,7］. A positive response to
steroid therapy in conjunction with the MRI, supports a diagnosis of a
pseudotumor.
We finally diagnosed our patient as having an orbital pseudotumor from the results of the MRI. Special attention was paid to the MRI in which the diffuse mass recovered with steroid therapy. The signal density was as high as the extraocular muscles before the steroid treatment.
Following the recovery with steroid therapy, the signal density decreased
gradually, but was still higher than that on the unaffected left eye even
though her subjective complaints were completely resolved.
We followed our patient with MRI, and 3 months after the subjective symptoms disappeared, the images became completely clear. The slower recovery of orbital pseudotumors demonstrated by MRI imaging suggests that the inflammation is still present even after the symptoms disappeared. Then we considered that one of the reasons for a high occurrence of the pseudotumor recurring might be due to earlier withdraw of steroid therapy when the symptoms are gone. In other words, the remained latent inflammation which our MRI demonstrated can increase by stopping steroids. We need to continue steroids therapy until all MR images become negative. |
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Acknowledgment
| The authors thank for Professor Duco Hamasaki, Bascom Palmer Eye Institute,
for editing the manuscript. |
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要旨
| 61歳女性，突然の頭痛，その後1週間ほどの右眼の深部眼窩痛，39℃の熱発があり，当科受診。眼痛の後，右眼眼球突出，眼瞼腫脹が生じた。眼球突出は21㎜であった。T2-MRIでは右眼窩内に高濃度の微慢性の陰影が認められた。眼筋，視神経は正常陰影であった。眼窩偽腫瘍の診断のもと，プレドニゾロン内服治療を開始した。臨床症状軽快とともにMR画像も徐々に回復していったが，MR画像の回復所見は臨床所見の回復より遅れていることが認められた。 |
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Others
1) Department of Ophthalmology and 2) Department of Oto-Rhino-Laryngology,
Sannoh Medical Center, Chiba 263-0002.
3) Department of Ophthalmology, Juntendo University Urayasu Hospital,
Urayasu 279-0021.
塙 勝博1)，安達惠美子1)，永田 博2)，溝田 淳3): 眼窩偽腫瘍治療経過中のMRI変化.
1) （翠）山王病院感覚器病センター眼科，2) 耳鼻咽喉科
3) 順天堂大学医学部附属順天堂浦安病院眼科
Tel. 043-421-2221. Fax. 043-421-1772.
2005年9月22日受付，2005年9月28日受理.
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