American Journal of Neuroradiology 27:270-273, February 2006
© 2006 American Society of Neuroradiology
CASE REPORT
HEAD AND NECK
Primary Intracranial Germinoma Presenting as a Central Skull Base Lesion
A.C. Douglas-Akinwandea,
A.A. Mourada,
K. Pradhanb and
E.M. Hattabc
a Department of Radiology, Indiana University School of Medicine, Indianapolis, Ind
b Department of Hematology and Oncology, Indiana University School of Medicine, Indianapolis, Ind
c Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, Ind
Address correspondence to Annette C. Douglas-Akinwande, MD, Department of Radiology, Indiana University Medical Center, University Hospital 0279, 550 N. University Boulevard, Indianapolis, IN 46202
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Abstract
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SUMMARY: We report an unusual case of primary intracranial germinoma
involving the sphenoid bone and sinus. To the best of our knowledge,
paranasal sinus and bone invasion of primary intracranial germinoma
has not been previously reported. Recognition of this rare form
of presentation by imaging is important because early radiation
and chemotherapy can result in a cure of this neoplasm.
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Introduction
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Germinomas, the most frequent intracranial germ cell tumors,
are rare tumors of children and young adults. They comprise
about 0.5%–3% of all primary central nervous system tumors.
1 The most common sites of involvement of intracranial germinomas
are the pineal and suprasellar regions,
2 but they can also involve
other locations, such as the thalamus and basal ganglia.
3 Germinomas
have a propensity to spread throughout the ventricular system
and subarachnoid spaces, and their ability to infiltrate adjacent
soft tissue structures has already been demonstrated.
4 We present
an unusual case of primary intrasellar germinoma that destroyed
the bony components of the central skull base and invaded the
sphenoid sinus at presentation.
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Case Report
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A 16-year-old Hispanic boy with a long-standing history of polyuria,
polydipsia, delayed puberty, and poor growth and development
presented with new-onset diplopia. His physical examination
was remarkable for short stature with height and weight less
than the fifth percentile for age-matched adolescents. He was
Tanner stage I and had signs of sixth nerve palsy. Diabetes
insipidus was suspected because of the complaints of polyuria
and polydipsia. Serum levels of alpha-fetoprotein (AFP) and
human chorionic gonadotropin (ßHCG) were undetectable.
MR imaging of the pituitary revealed a large, solid mass with its epicenter in the sella turcica, extension into the suprasellar cistern and hypothalamus superiorly, sphenoid sinus inferiorly, and cavernous sinuses bilaterally. Total encasement of the left internal carotid artery with mild stenosis and partial encasement of the right internal carotid artery were noted. The optic chiasm and hypothalamus were compressed. The lesion exhibited isointense signal intensity on T2-weighted (Fig 1A), fluid-attenuated inversion recovery (FLAIR; Fig 1B), and T1-weighted images (Fig 1C). It enhanced heterogeneously on contrast enhanced T1-weighted images (Figs 1D, -E). An MR imaging of the spine was normal.
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Fig 1. A–D, MR images from 16-year-old boy who presented with a long-standing history of poor growth, delayed puberty, polydipsia, and polyuria.
A, Transverse T2-weighted image at the level of the cavernous sinuses shows an isointense mass involving the sella turcica, posterior sphenoid sinus, left greater than right cavernous sinus, the left middle cranial fossa, and the prepontine cistern.
B, FLAIR-weighted image at the level of the cavernous sinuses shows an isointense mass involving the sella turcica, posterior sphenoid sinus, left greater than right cavernous sinus, the left middle cranial fossa, and the prepontine cistern.
C, Midline sagittal T1-weighted image shows an isointense mass involving the basiocciput portion of the clivus, the sella turcica, the sphenoid sinus (short arrow), and the suprasellar cistern. The expected hypointense posterior cortex is absent (long arrow).
D, Midline sagittal contrast-enhanced T1-weighted image shows a heterogeneously enhancing mass involving the basiocciput portion of the clivus, the sella turcica, the sphenoid sinus, the suprasellar cistern, and the hypothalamus.
E, Coronal contrast-enhanced T1-weighted image at the level of the sella shows a heterogeneously enhancing mass involving the basiocciput portion of the clivus, the sella turcica, the sphenoid sinus, the suprasellar cistern, and the hypothalamus. There is extension into the left greater than the right cavernous sinus with encasement and stenosis of the left internal carotid artery. The typical hypointense cortex of the floor of the sella is not visible. The mass appears to abut the nasopharynx.
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The patient underwent a thorough neurosurgical assessment, and it was concluded that the lesion was not completely resectable. Following hormonal stabilization, decompression surgery was performed via a trans-sphenoidal approach. Specimens from the suprasellar and sphenoid sinus components of the mass, as well as CSF samples, were submitted for histopathologic evaluation. This revealed a highly cellular neoplasm comprising sheets and lobules of polygonal tumor cells traversed by fibrous septae rich in lymphocytes. The tumor cells were characterized by large round nuclei and prominent nucleoli. They wrapped around and invaded bone and cartilage, including the epithelium, and covered sphenoid sinus walls (Figs 2A, -B). The tumor cells showed weak reactivity to placental alkaline phosphatase but were strongly and diffusely reactive for OCT4 nuclear stain, which confirmed the diagnosis of germinoma.5 Immunoreactivity for AFP, ß-HCG, epithelial membrane antigen (EMA), cytokeratin, and chromogranin were appropriately absent. A CSF sample collected via lumbar puncture was negative for tumor cells.
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Fig 2. A, Low-power image shows sheets of germinoma cells invading and wrapping around the bone and cartilage of the sphenoid process (left upper) (40x, hematoxylin and eosin).
B, High-power image depicts direct invasion of germinoma tumor cells (right side) into adjacent bone and cartilage (200x, hematoxylin and eosin).
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The patient was treated with craniospinal irradiation (CSI) with a boost to the tumor bed involving the sella and the sphenoid region. He received 2340 cGy to the craniospinal axis, a boost of 1260 cGy to the ventricles, and an additional 1440 cGy to the sella and the sphenoid area, thereby increasing the tumor bed dose to 5040 cGy. Radiation therapy, delivered during a 6-week period, was well tolerated by the patient. No chemotherapy was administered.
The patient has been closely followed by an ophthalmologist, to monitor for visual field deficiencies, and by an endocrinologist, to monitor for hypopituitarism. He has received desmopressin for treatment of diabetes insipidus. He also receives maintenance doses of corticosteroids and synthyroid for hypocortisolemia and hypothyroidism respectively. Surveillance MR imaging of the brain obtained annually has shown no evidence of recurrence (Figs 3A, -B). The patient continues to receive growth hormone replacement therapy. He has shown adequate growth velocity. At his most recent follow-up visit, 28 months after cessation of radiation therapy, he was without evidence of tumor recurrence and his ophthalmic examination was stable.
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Fig 3. A, Midline sagittal T1-weighted image shows no residual mass.
B, Midline sagittal contrast-enhanced T1-weighted image shows no residual mass or pathologic enhancement.
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Discussion
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Germinomas are thought to arise from a midline streaming of
totipotential cells very early in rostral neural tube development
or from abnormal implantation in the midline during the migration
of germ cells that result in the formation of the urogenital
ridge.
6 Local spread of intracranial germinoma within the brain
and throughout the subarachnoid space,
7 including synchronous
lesions, is not uncommon. This type of spread, however, is usually
limited to the soft tissues within the cranial cavity showing
little or no propensity toward bone invasion. Primary intrasellar
germinomas are rare.
8 They may develop as secondary intrasellar
extension of primary suprasellar tumors
9 or originate as primitive
intrasellar growth. A germinoma may be designated as primary
intrasellar if the lesion exclusively resides within the sella
turcica or if both intrasellar and extrasellar components are
present.
10,
11 In advanced stages, however, the site of origin
cannot be differentiated and tumor may traverse the hypophyseal-hypothalamic
axis (HHA). The epicenter of the germinoma in our patient was
in the sella turcica (
Fig 1); hence, it is classified as a primary
intrasellar germinoma. The patient’s long-standing history
of signs and symptoms of panhypopituitarism, which is atypical
for HHA lesions, supports the primary intrasellar origin of
this germinoma.
Our case is unique in demonstrating direct invasion and destruction of the sphenoid bone and basiocciput, which are the major components of the central skull base. Furthermore, overt invasion of the floor of the sella with extension into the sphenoid sinus has not been previously reported. This patient had no complaints of paranasal sinus symptoms, though, like other patients with cavernous sinus invasion and HHA lesions, he had symptoms of both visual disturbance and diabetes insipidus.10–14 The isointense signal intensity on MR imaging, contrast enhancement,2 extension along the HHA8,10,13 and into the cavernous sinuses are typical10 of HHA germinomas. This case clearly demonstrates that germinomas may present as central skull base lesions and therefore should be included in the differential diagnosis. The presence of bone destruction with extension into the adjacent paranasal sinuses, though rare, should not dissuade the radiologist from suggesting the diagnosis of primary intracranial germinoma in the appropriate clinical setting.
CSF dissemination of primary intracranial germinoma throughout the ventricular system and subarachnoid space is common4,7; therefore, before any surgical intervention, MR imaging of the entire spine with contrast is essential for the detection of metastasis.7,15
Surgery is required for histologic confirmation of the diagnosis, and no attempt to achieve total resection is usually made, because germinomas are exquisitely sensitive to radiation and chemotherapy.16 The patient presented here responded well to CSI, which has long been regarded as the conventional therapy for intracranial germinomas. There is, however, an increasing trend toward use of the combined approach of adjuvant chemotherapy and radiation in an effort to reduce the dose and/or field of radiation and ultimately decrease the late effects of radiation therapy in young, developing patients.16
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Conclusions
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Although histologic sampling is necessary for definitive diagnosis,
we propose that primary intracranial germinoma should be considered
in the differential diagnosis of central skull base lesions
in children or young adults, especially those presenting with
signs of pituitary dysfunction and diabetes insipidus. Recognition
of this rare form of presentation by imaging is important because
early radiation and/or chemotherapy can result in a cure of
an otherwise locally destructive neoplasm.
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Footnotes
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This study was presented, in part, at the 2004 scientific assembly
and annual meeting of the American Society of Head and Neck
Radiology, Philadelphia, Pa, September 29–October 3, 2004.
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References
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- Liang L, Korogi Y, Sugahara T, et al. MRI of intracranial germ-cell tumours. Neuroradiology 2002;44:382–88[Medline]
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Received February 11, 2005;
accepted after revision May 9, 2005.
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Abstract
Introduction