AJR 2004; 182:1605-1606
© American Roentgen Ray Society
Amyloidoma of Meckel's Cave: A Rare Cause of Trigeminal Neuralgia
Eugene Yu and
Lyne Noel de Tilly
University of Toronto Toronto, ON M4Y 2W4, Canada
Amyloid is an abnormal, insoluble protein that can become deposited in the
extracellular space [1]. It can
involve virtually any organ system and may manifest as a systemic process or
as a focal lesion (amyloidoma). We present a rare case of central nervous
system amyloidoma located in Meckel's cave in a patient presenting with
trigeminal neuralgia.
A 62-year-old man presented with symptoms of chronic left-sided trigeminal
neuralgia. Examination revealed a 30 pack-year smoking history, hypertension,
and hiatal hernia. Routine laboratory findings were unremarkable. The patient
was currently taking gabapentin, valsartan (Diovan, Novartis), ranitidine
hydrochloride, and acetaminophen with codeine.
MRI of the head revealed a focal lesion located in the left Meckel's cave
measuring 1.4 x 0.7 cm (anteroposterior x transverse dimensions).
The lesion was isointense on T1-weighted imaging and hypointense on
T2-weighted imaging and showed uniform enhancement (Fig.
3A,
3B,
3C). The low signal intensity
was considered to be unusual for a lesion such as a schwannoma. The patient
was referred for surgery and underwent a left suboccipital craniotomy and
biopsy. Findings at gross pathology revealed pinkish tissue. Microscopic
results showed a small segment of well-myelinated peripheral nerve infiltrated
by confluent masses of tissue staining intensely positive with Congo red.
Immunostaining was positive for lambda and transthyretin. These staining
features were supportive of a diagnosis of amyloidoma.
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Fig. 3A. —62-year-old man who presented with chronic left-sided
trigeminal neuralgia. Axial T1-weighted image (TR/TE, 700/15) obtained at
level of skull base shows asymmetric isointense soft tissue in region of left
gasserian ganglion (arrowheads).
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Fig. 3C. —62-year-old man who presented with chronic left-sided
trigeminal neuralgia. Coronal gadolinium-enhanced T1-weighted image (500/14)
obtained in same plane as B shows lesion to be uniformly enhancing.
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Amyloid is an abnormal process that can affect various organ systems. Men
are thought to be affected more often than women. Classification schemes
include subdivision into systemic or focal disease or into primary or
secondary disease. Cases with familial tendency have also been noted. Amyloid
deposition can arise secondary to long-term hemodialysis, myeloma, and chronic
inflammatory conditions such as osteomyelitis, rheumatoid arthritis, and
tuberculosis. This disease rarely involves the central nervous system.
Presentation varies depending on lesion location and includes paresis,
dysarthria, and seizure.
Neuroimaging can play an important role in patient evaluation by revealing
the presence of a structural abnormality. The location, extent of disease, and
number of lesions can then be determined. In some instances, diagnosis of a
specific lesion can be attempted. In this case, the low signal on T2-weighted
sequences was considered unusual for a more common lesion such as a
schwannoma. Past reports on cerebral parenchymal amyloid have yielded varying
signal characteristics with MRI
[2–4].
These reports have cited lesions of low, intermediate, high, and heterogeneous
signal intensity on both T1- and T2-weighted sequences. The signal intensity
of the lesion in our patient was the same as that noted by Vorster et al.
[4], with the lesion showing
isointensity on T1- and hypointensity on T2-weighted imaging.
In summary, we present a case of trigeminal neuralgia that developed
secondary to an amyloidoma affecting the gasserian ganglion. This entity
should be considered in the differential diagnosis of lesions involving
Meckel's cave.
References
- Cotran RS, Kumar V, Robbins SL. Robbins pathologic basis
of disease, 4th ed. Toronto, ON: WB Saunders, 1989:163
–237
- Lee J, Krol G, Rosenblum M. Primary amyloidoma of the brain: CT and
MR presentation. AJNR1995; 16:712
–714[Abstract]
- Symko SC, Hattab EM, Steinberg GK, Lane B. Imaging of cerebral and
brain stem amyloidomas. AJNR2001; 22:1353
–1356[Abstract/Free Full Text]
- Vorster SJ, Lee JH, Ruggieri P. Amyloidoma of the gasserian
ganglion. AJNR1998; 19:1853
–1855[Abstract]
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