A 20-year-old female presented with left-sided headache and progressive
sensorineural hearing loss. There was also a history of chronic left-sided
visual impairment. Findings on the initial head CT prompted dedicated temporal
bone CT and MR imaging, and then preoperative catheter angiography. Shortly
afterward, the patient underwent surgical resection of a left temporal bone
The temporal bone CT scan demonstrates an area of extensive
retrolabyrinthine destruction. The inferior aspect of the lesion involves the
posterior border of the jugular fossa, and there is also extension into the
middle ear cavity. There are spicules of residual bone throughout the involved
region. The MRI examination demonstrates a mass with T2-hyperintensity and
robust enhancement, corresponding to the area of bone destruction seen on the
CT. There are also areas of intrinsic T1-hyperintensity on the noncontrast
images. In order to decrease blood loss during surgery, a preoperative
angiogram was performed for embolization of the mass before surgical resection.
The angiogram demonstrates a hypervascular mass with arterial supply from the
ascending pharyngeal artery.
and coronal (B) images from a CT examination of the temporal bones. There is
osseous destruction of the retrolabyrinthine portion of the left temporal bone,
with spiculated fragments of residual bone (arrow in A). The inferior aspect of
the process involves the jugular fossa and middle ear cavity (arrows in
Photos courtesy of M. Ghesani, MD
The temporal bone lesion is an endolymphatic sac tumor (ELST). In this
particular case, involvement of the jugular fossa and middle ear cavity may
raise the question of paraganglioma. However, the mass is centered in the
retrolabyrinthine area. This location, and the residual bone fragments visible
on the CT, are classic for ELST.
The heterogeneous T1 hyperintensity is typical, from proteinaceous
content/blood products. ELST is a highly vascular lesion, supplied from the
ascending pharyngeal artery or posterior auricular artery (stylomastoid
branch). On MRI, vascular flow voids may be visible in tumors larger than 2 cm,
which may also make distinction from paraganglioma difficult. Preoperative
embolization is helpful in larger, more vascular tumors.
Axial images from an
MRI examination of the brain. There is T1 signal hyperintensity within the left
temporal bone lesion (arrow in A). There is also marked enhancement of the
lesion (B). The mass also demonstrates predominantly hyperintense T2 signal
(C). Note also the abnormal T1 signal intensity of the left ocular globe
(arrowhead in A).
Patients with ELST who present with vestibulocochlear symptoms may have
no visible tumor on imaging, although endolymphatic hydrops or blood products
may be present. Hearing loss is the most common presenting symptom and may be
acute or stepwise. Other symptoms will depend upon the involvement of adjacent
structures, such as the lower cranial nerves.
Histologically, ELST is a low-grade papillary adenocarcinoma, but may
resemble the papillary cystadenoma of the epididymis/broad ligament seen in
patients with von Hippel-Lindau syndrome (VHL). Unfortunately, light microscopy
of ELST may also resemble several of the important entities in the imaging
differential diagnosis, especially paraganglioma, but also thyroid and renal
metastases or middle ear adenocarcinoma. Immunohistochemistry may help, but
clinical and radiologic features are essential.
Lateral view from a catheter
angiogram. There is a hypervascular mass (large arrow) with arterial supply
from a prominent ascending pharyngeal artery (small arrow).
VHL has been linked to chromosome 3. Sporadic ELST is rare, but may be
seen with higher frequency in the setting of VHL. Bilateral ELST occur more
frequently in patients with VHL than do sporadic ELST. Many clinicians advocate
screening audiometric and imaging studies to detect subclinical ELST in
patients with VHL, as well as screening abdominal imaging due to the high
incidence of tumors of the pancreas, adrenal glands and kidneys. Although ELST
is locally destructive, metastases are very rare.
In this particular case, a key finding is the left ocular hemorrhage,
manifesting as T1 and T2 signal abnormality on the MR images. Given the imaging
findings that are consistent with ELST, the ocular abnormality may be presumed
to be due to a retinal hemangioma, leading to the further diagnosis of VHL.
Daniel E. Meltzer, MD, is an assistant professor of radiology at St
Luke’s-Roosevelt Hospital Center.
Munir Ghesani, MD, is an attending radiologist at St.
Luke’s-Roosevelt Hospital Center and associate clinical professor of
radiology at Columbia University College of Physicians and Surgeons.
Disclosures: Drs. Ghesani and Meltzer report no relevant
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