Thyroid Ophthalmopathy: Bony Erosion on CT and Increased ... · Thyroid Ophthalmopathy: Bony...

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472 Thyroid Ophthalmopathy: Bony Erosion on CT and Increased Vascularity on Angiography John F. He aly ,1 J. H. Metcalf, 2 and Falke J. Br ahme 1 A pat ient with bio psy-prov en Graves ophthalmop athy is described, wit h the unusual and previously unre ported CT finding of erosion of th e bony roof of the orbit. Internal ca rotid arteriography revealed diffuse increased vascularity through out the orbit. We were unable to find any previous desc ription of the angiographi c findings in thyroid ophthal- mopathy . Case Report A 21-year-old man had gradually increasing unilateral pro pt osis of the right eye. His history was remark able in that he had had a subt ota l thyroidecto my several years earli er for Graves disease. He remained euthyroid on no thyroid medi cation and was , on admis- sion, euthyroid with normal T3 and T4 . His vi sion had r ecently deteri orated from 20 / 20 to 20/ 50 00, but had returned to normal when he was pl aced on steroid therapy. Ph ys ica l examination was entirely normal, exce pt f or mark ed pro pt osis and marked conjun c- tival injec tion of the right eye. Plain films of the orbits were unr emarkabl e. Opti c canal tomo- grams were normal. Axial (fig. 1 A) and co ronal (figs. 1 B and 1 C) CT scans revealed a slightly enhancing mass in the super ior apex of the ri ght orb it with evidence of smoo thly marginated bone erosion on the posterior and supe ri or wa ll of that orbit. There was obvious exop ht halmus and thinning of the ri g ht orbital roof. The superior orbi tal mass appeared bilobed. The possibility of enlar ged superior rec tus and super ior oblique muscles was entertained. Both medial rect i muscles appeared slightly prominent on the axial sca ns, but loo ked less enlarged on the co ronal sca ns. Ri g ht ex ternal carotid arteri og raphy revealed no abnormaliti es . Right internal carotid ar- t er iog raphy (fig. 2) revealed str etching of the ophthalmic artery and its branches by a mass . A diff use homogenous vasc ular stain, most prominent in the apex, was noted in the capillary phase along with many sma ll irregular vessels. The increased vasc ularit y and pud- dling perSisted somewhat into the venous phase. The left int ernal ca rotid angiog ram was normal. Bec ause of the p ossibility of a solid tumor, a right fr ontal crani- oto my with extensive rig ht or bital d eco mpress ion was performed. The bony orbital roo f was markedly thinn ed. The superi or oblique and superi or rec tus mu sc les were hypert rop hied to 8 -10 times normal size. No tumor was found. A sp ec imen was s ubmitted for path olog ic st udy . Received January 14 , 1 98 1; acce pted March 1 7, 198 1. Pathologi cal samples ex hibit ed a variegated admixtur e of lym- phocytic infil tr ates and degenerative chang es within skeletal mus- cle ; the spec trum was quit e char ac teristic of the o phth almopathy assoc iated with Graves disease. Small, we ll differentiated lympho- cy t es were the most co nspic uous inflammatory c ompon ent , with ad ditional scatt ered pl asma cells and eosinophils. A r eac tive vas- cular bac kgro und was particularly striking , with numero us dilated cap ill ar ies , arterioles, and venul es (fig. 3A). In some areas the inflammatory ce ll s s ur r ound ed groups of skeletal mu sc le fibers, sugg estive of a myositis. Par ts of extr aoc ular muscle ex hibited a variable increase in fiber diameter and zones of basophilic or mucinous degeneration within the sarco plasm. The fibers were widely separated by layers of loose coll agen with increase in mu cop oly sacc haride ground s ubst ance (fig. 3B). Discussion The usual spectrum of findings of thyroid ophthalmopathy in cranial computed tomography has been well described [1-5]. Bilateral extraocular muscle enlargement , either sym- metric or asymmetric (30 %), has been reported in the vast majority of patients with thyroid ophthalmopathy . None of the 11 6 patients in the largest reported series exhibited abnormal orbital soft tissues other than enlarged muscles. While s uperior rectus involvement wa s seen in 50 % of the patients, superior oblique muscle involvement was distinctly unusual [1]. In another study by Wing et al. [2] , using direct sagittal CT scanning, involvement of the superior rectus was seen in 17 of 24 patients. Bony thinning and erosion can be seen in orbital masses. If the bony changes are of a permeative destructive type, either direct extension from adjacent malignant processes from the paranasal sinuses or from distant sites (especially lung, breast , and prostate) are often the cause . Benign lesions such as hemangiomas, dermoids, or venous malfor- mations can produce well marginated erosions . Lloyd [15] states that generalized enlargement of th e bony orbit is usually the result of longstanding space-occupying lesions The opinions or assertions ex pressed herein are those of the authors and are not to be con strued as offici al or as reflecting the vi ews of the Department of the Navy or the Naval Ser vi ce at large. 'Department of Radiolog y, University of California Medi cal Center, 225 Di ck inson St., San Diego, CA 92103 . Address reprint requests to J. F. Healy. 2Department of Pathology , Naval Regional Medical Center, San Di ego, CA 921 34 . AJNR 2 :472- 474, September /Oct ober 1981 0195 -6 108 / 81 / 0205-472 $00 . 00 © American Roe ntgen Ray Society

Transcript of Thyroid Ophthalmopathy: Bony Erosion on CT and Increased ... · Thyroid Ophthalmopathy: Bony...

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Thyroid Ophthalmopathy: Bony Erosion on CT and Increased Vascularity on Angiography John F . Healy ,1 J. H . Metcalf, 2 and Falke J . B rahme1

A patient with biopsy-proven Graves ophthalmopathy is described , with the unusual and previously unreported CT finding of erosion of the bony roof of the orbit. Internal carotid arteriography revealed diffuse increased vascularity throughout the orbit. We were unable to find any previous description of the angiographic findings in thyroid ophthal­mopathy.

Case Report

A 21-year-old man had gradually increasing unilateral proptosis of the right eye . His history was remarkable in th at he had had a subtotal thyroidectomy several years earlier for Graves disease. He remained euthyroid on no thyroid medication and was, on admis­sion, euthyroid with normal T3 and T4 . His vision had recently deteriorated from 20/ 20 to 20 / 50 00, but had return ed to normal when he was placed on steroid therapy. Physical examination was entirely normal, except for marked proptosis and marked conjunc­tival injection of the right eye.

Plain films of the orbits were unremarkable. Optic canal tomo­grams were normal. Axial (fig . 1 A) and coronal (figs. 1 B and 1 C) CT scans revealed a slightly enhanc ing mass in the superior apex of the right orbit with evidence of smoothly marginated bone erosion on the posterior and superior wall of that orbit. There was obvious exophthalmus and thinning of the right orbital roof. The superior orbi tal mass appeared bilobed . The possibility of enlarged superior rectus and superior oblique musc les was entertained. Both medial rect i muscles appeared slightly prominent on the axial scans, but looked less enlarged on the coronal scans. Right external carotid arteriog raphy revealed no abnormalities. Right internal carotid ar­teriography (fig. 2) revealed stretching of the ophthalmic artery and its branches by a mass. A diffuse homogenous vascular stain , most prominent in the apex , was noted in the capillary phase along with many small irregular vessels. The increased vascularity and pud­dling perSisted somewhat into the venous phase. The left internal carotid angiog ram was normal.

Because of the possibility of a solid tumor, a right frontal c rani­otomy with extensive right orbital decompression was performed. Th e bony orbital roof was markedly thinned . The superior oblique and superior rectus muscles were hypertrophied to 8-10 times normal size. No tumor was found. A specimen was submitted for patholog ic study.

Received January 14 , 1981; accepted March 17, 1981.

Pathological samples exhibited a variegated admixture of lym­phocytic in fil trates and degenerative changes within skeletal mus­cle; the spectrum was quite characteristic of the ophthalmopathy associated with Graves disease. Small , well differentiated lympho­cytes were the most conspicuous inflammatory component, with additional scattered plasma cells and eosinophils . A reactive vas­cular background was parti cularly striking , w ith numerous dilated capillaries, arterioles , and venules (fig . 3A). In some areas the inflammatory ce lls surrounded groups of skeletal muscle fibers, suggestive of a myositis .

Parts of extraocular muscle exhibited a variable increase in fiber diameter and zones of basophilic or muc inous degeneration within the sarcoplasm. The fibers were widely separated by layers of loose collagen with increase in mucopolysaccharide ground substance (fig . 3B) .

Discussion

The usual spectrum of findings of thyroid ophthalmopathy in cranial computed tomography has been well described [1-5]. Bilateral extraocular muscle enlargement, either sym­metric or asymmetric (30%), has been reported in the vast majority of patients with thyroid ophthalmopathy. None of the 11 6 patients in the largest reported series exhibited abnormal orbital soft tissues other than enlarged muscles. While superior rectus involvement was seen in 50% of the patients, superior oblique muscle involvement was distinctly unusual [1]. In another study by Wing et al. [2], using direct sagittal CT scanning , involvement of the superior rectus was seen in 17 of 24 patients.

Bony thinning and erosion can be seen in orbital masses. If the bony changes are of a permeative destructive type, either direct extension from adjacent malignant processes from the paranasal sinuses or from distant sites (especially lung , breast, and prostate) are often the cause. Benign lesions such as hemangiomas, dermoids, or venous malfor­mations can produce well marginated erosions . Lloyd [15] states that generalized enlargement of the bony orbit is usually the result of longstanding space-occupying lesions

The opinions or asserti ons expressed herein are those of the authors and are not to be construed as official or as refl ecting the vi ews of the Department of the Navy or the Naval Servi ce at large.

' Department of Radiology, University of Cali fornia Medical Center , 22 5 Dickinson St. , San Diego, CA 92103. Address reprint requests to J . F. Healy. 2Department o f Pathology, Naval Regional Medical Center , San Diego, CA 9 2 134.

AJNR 2 :472-4 74, September/ October 1981 0 19 5-6108 / 81 / 0205-472 $00.00 © American Roentgen Ray Society

AJNR :2, September/ October 1981 CT / ANGIOGRAPHY OF THYROID OPHTHALMOPATHY 4 73

A B Fig. 1.-A, Axial CT scan with contrast . Slightl y enhanc ing mass (M) in

superoposterior right orbit. Moderate enlargement of both medial recti (ar­rowheads). Remodeling of posterior bony wall of right orbit (arrow). Obvious

A B Fig . 2. -A, Arterial phase, selective internal carotid injecti on. Marked

stretching (arrow) of ophthalmic artery. B , Orbital capillary phase. Multiple irregular small vessels (arrow) and diffuse stain predominating at orbital apex.

causing raised intraorbital pressure and that orbital en large­ment is important in differentiating a space-occupying lesion from unilateral exophthalmus of endocrine origin .

In the orbit, there are two ways in wh ich carotid angiog­raphy may reveal an abnormality ; either by the displacement of vessels or by demonstration of pathologic circulat ion . Thus, examination may be of help in revealing both the site and the nature of the lesion [15]. However, we have been unable to find a description in the literature of the arterio­graphic findings in thyroid ophthalmopathy [6-1 6]. Hanafee and Dayton [12] describe "irregular arteries in the late arterial phase and a distinct tumor-like staining caused by contrast-laden capillaries in the capillary phase " on an arteriogram done on a patient with unilateral exophthalmus caused by pseudotumor of the orbit. They ascribe the " tu­mor stain " to areas of cell ular inflammation consistent with pseudotumor. Another vascular method of investigation , orbital venography, shows only nonspecific findings in pa-

c rig ht exophthalmus. B, Coronal scan (level 189 EMI units, window 400 EMI units). Thinning (arrow) of bony roof of right orbit . C, Coronal conventional scan (level 0 , window 200 EMI units). Large superior right orbital mass (M).

c Slight flattening of choroid c rescent by mass effect (arrowhead ). C, Venous phase. Persistent abnormal vasculari ty and puddling of contrast (arrowhead).

ti ents with endocrine exophthalmus. Orbital myositis is often noted in these patients and the orb ital veins may be dilated , especially adjacent to the involved eye muscles. However, Doyon et al. [16] found that orbital venography was of li ttle help in differentiating malignant exophthalamus of endocrine cause from other lesions of the orbit . The fl ow in the superior ophthalmic vein may be blocked as intraorbital pressure increases , but th is was a nonspecific finding also seen in many mass lesions.

We believe that the bone erosion and expansion demon­strated in our case was the result of direct pressure erosion by the huge superior rectus and superior oblique musc les. Thinning and resorption of bone may have also resulted from the diffuse hyperemia in the orbit. The numerous dilated capillaries, arterioles, and venules noted in the path­ologic specimen forms the basis for the angiographic find­ings of increased vascularity and dilated small vesse ls in the late arterial, capillary, and venous stages.

474 HEALY ET AL. AJNR:2 , September / October 1981

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