Singapore Med J 2006; 47(1) : 65
A 69-year-old man who presented with
incidental hypoglobus was found to have
an isolated superior rectus mass. Diagnosis
of primary amyloidosis of superior rectus
was made on incisional biopsy and negative
systemic work-up. This
manifestation and site for amyloidosis and
should be a differential of any extraocular
is an unusual
Keywords: extraocular mass, hypoglobus,
orbit, primary amyloidosis, superior rectus
Singapore Med J 2006; 47(1):65-67
Primary localised orbital amyloidosis is a rare
condition, with isolated involvement of extraocular
muscle being even less common. The clinical,
radiological and histopathological findings of a
case of localised orbital amyloidosis involving the
superior rectus muscle are presented.
A 69-year-old Chinese man presented with a
complaint of mild blurring of right eye vision for
three months. Clinical examination showed reduced
visual acuity of 6/24 and 6/18 in the right and
left eyes, respectively, from moderate cataracts.
Refraction did not reveal
astigmatism. He did not complain of diplopia
and denied any history of trauma. An incidental
asymptomatic finding of mild right hypoglobus
with upper lid fullness was noted. Careful
examination revealed a smooth, pinkish-white
vascular mass overlying the right superior rectus.
The posterior edge was not palpable (Fig. 1).
Restriction of right
hypoglobus were demonstrated on Hess test. The
right levator palpebrae superioris function and
fundus examination were normal, and there
was no proptosis on exophthalmometry. Non-
eye elevation and
Incidental hypoglobus: primary
amyloidosis of the superior rectus
Teoh S C B, Liew G C, Yap W M
The Eye Institute
Tan Tock Seng Hospital
11 Jalan Tan Tock Seng
Teoh S C B, MMed,
Liew G C, MMed,
Yap W M, MPath,
Dr Stephen C B Teoh
Tel: (65) 6357 7726
Fax: (65) 6357 7718
C a s e R e p o r t
ophthalmic physical examination was essentially
normal. Computed tomography (CT) of the orbits
performed with contrast enhancement showed
a large well-defined mass in the superior orbit
enveloping the superior muscle complex (Fig. 2).
The superior rectus was thickened including the
tendinous insertion, and enhanced (Fig. 3). The
lacrimal gland and other recti muscles were normal.
Fig. 1 Lateral photograph shows a smooth elevated pink
vascular lobulated mass over the superior rectus.
Fig. 2 Coronal CT image shows a well-defined mass in the
superior orbit enveloping the superior rectus complex.
Singapore Med J 2006; 47(1) : 66
from the overlying conjunctiva and episclera, with
minimal bleeding during biopsy. Histopathological
examination demonstrated an amorphous mass with
hyaline eosinophilic features on haematoxylin and
eosin stain, and green birefringence with congo red-
stain under polarised light consistent with amyloid
(Figs. 4 & 5). Systemic review and investigations
by the internist targeted at establishing secondary
amyloidosis, were negative. In particular, the liver
function tests, serum immunoglobulin levels, serum
and urine electrophoresis for Bence-Jones proteins
were all normal. Diagnosis of primary superior
rectus amyloidosis was made.
On initial follow-up, the patient remained well
with no systemic manifestations. However, the
lesion gradually enlarged again after three years,
resulting in upgaze restriction that required a repeat
Amyloidosis is an idiopathic disease characterised
by deposition of a heterogeneous proteinaceous
extracellular material which may be found in any
organ or tissue in the body. It is typically classified
into primary, occurring de novo; or secondary to
an underlying disease, which can be localised or
systemic as characterised by multiple myeloma(1).
Localised amyloidosis is rare and its pathogenesis is
largely unknown. It has been reported that only 4%
of localised amyloidosis of the head and neck occur in
the eye and orbits(2). In the eye, amyloidosis more
commonly affects the eyelids, conjunctiva and
lacrimal gland, and is postulated to be a result of
chronic inflammation such as trachoma(1-4). Orbital
involvement and infiltration of the extraocular
muscles is rare and usually occurs in isolation.
To date, there have been only six other reports of
isolated extraocular muscle involvement(2,4-8).
Clinically, the most common presentation is a
painless, palpable mass(2), as in our patient. Other
presentations include proptosis, globe displacement,
astigmatism and diplopia secondary to restricted
motility(2). Gross appearance of the lesion is often
non-characteristic and ranges from a firm, pale, waxy
amorphous mass to a pink, variegated lesion which
may be easily mistaken for other ocular pathology
such as lymphoma or metastatic tumours.
Radiological features are also non-characteristic.
CT is the most commonly – used radiological
investigation. Amyloid deposition in the recti has
been noted to present with muscle enhancement
and enlargement involving the tendinous insertions,
features which were seen in our case. It may mould
to adjacent orbital wall and globe and show adjacent
In view of the clinical and radiological findings,
an incisional biopsy was carried out. The mass was
approached through the superior bulbar conjunctiva
and revealed a smooth, soft, yellowish mass with
no significant capsule. It was easily separated
Fig. 5 Photomicrograph shows apple-green birefringence in
polarised light (Congo red stain, x10).
Fig. 3 Axial CT image of the orbits shows a lesion extending
anteriorly to involve the tendon at the point of insertion.
Fig. 4 Photomicrograph of the biopsy specimen shows nodules
of amyloid (Haematoxylin & eosin stain, x20).
Singapore Med J 2006; 47(1) : 67 Download full-text
bony changes. Focal thinning and erosion, and
hyperostotsis have been described(2,9). On magnetic
resonance imaging, amyloid may present as an
area of heterogeneous hypodensity on T2-weighted
images. On the fat-saturated contrast enhanced
images, it appears as an area of marked homogeneous
enhancement(9). However, these findings are not
specific to amyloid and may be confused with other
diseases including granulomatous inflammation,
lymphoproliferative disease, metastasis, and vascular
disorders such as a cavernous haemangioma.
Definitive diagnosis is made through a biopsy
of the lesion. Light microscopy of the specimen
shows an eosinophilic extracellular substance that
has an apple-green birefringence with polarised light
and congo red stain. Histochemical differentiation
can be made after pre-treatment with potassium
permanganate (KMnO4)(3). Other investigative tools
may include electron microscopy that demonstrates
characteristic 70-100Ao non-branching fibrils and
β-pleated sheets on X-ray diffraction(3).
investigation for an underlying systemic disease
and especially paraproteinaemia. Tests may include
chest radiographs, 2D-echocardiogram, serum and
urine electrophoresis for Bence-Jones proteins,
rheumatoid factor and anti-nuclear DNA. A rectal
or abdominal fat pad biopsy is performed, when
necessary, to confirm the diagnosis as these are
positive for systemic amyloidosis in 80% of cases(7).
No effective treatment is available but extraocular
muscle dysfunction with no significant enlargement
may respond to strabismus surgery(7). A large
tumour causing troublesome visual symptoms or
unsightly cosmesis may be best managed with
The diagnosis of amyloidosis is an uncommon
entity in the ophthalmological practice. It is often
confused with other orbital pathologies and an
incisional biopsy should always be performed
to obtain histological diagnosis. This differential
should be kept in mind for an atypical orbital lesion
as there are potential serious systemic complications
associated with it, although more often than not,
it is isolated and benign.
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aspiration diagnosis of orbital plasmacytoma with amyloidosis:
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