Key-words:
Germinoma - subarachnoid dissemination - tubercular meningitis
Introduction
The primary intracranial germ cell tumor (GCT) is rare constituting only a small percentage
of all intracranial tumors. The most common GCT is germinoma, with the suprasellar
region being the most favored site.[[1]] The most common mode of presentation is compression over the adjacent structures
with raised intracranial pressure, visual defects, and neuroendocrine symptoms. Cerebrospinal
fluid (CSF) spread has been known, but subependymal spread with CSF dissemination
along the basal cistern as primary presentation is extremely rare. The aim of reporting
this case is to illustrate the unusual presentation clinically and radiologically
mimicking tubercular meningitis/periventricular lymphoma, causing the wrong primary
diagnosis, and only histopathological examination could make the diagnosis of true
neoplastic nature of the lesion.
Case Report
A 20-year-old male referred to our neurosurgical clinic as a case of multiple periventricular
mass, suspected tuberculomas, with obstructive hydrocephalus on anti-tubercular therapy
for 2 months. The available previous records of the patients showed a history of difficulty
in walking (generalized weakness) for 2 months and altered sensorium for 5 days; there
was no other significant history. Magnetic resonance imaging (MRI) brain showed prominent
nodular hyperintensities around the left occipital horn, bilateral frontal horns,
right thalamic region, and altered signal intensities in the corpus callosum [[Figure 1]]. The patient was managed conservatively and was discharged (no details were available).
The patient again presented, 3 months later, with complaints of altered sensorium
and no motor deficit. Routine blood and CSF investigations were within normal limits.
The available images showed progression of the lesion with diffuse involvement of
the left occipital horn, third ventricle, and bilateral frontal horn with the appearance
of new solid-cystic lesions around the frontal horn and pineal region. Magnetic resonance
spectroscopy showed lipid peak [[Figure 2]]. The patient was started on anti-tubercular therapy with steroids on a suspicion
of multiple tuberculomas as a differential diagnosis. The patient improved clinically
and was discharged. Now, the patient again presented to the neurosurgery emergency
of the same hospital with complaints of multiple episodes of vomiting and generalized
weakness. Noncontrast computed tomography (NCCT) scan of the brain showed significant
diffuse nodular densities around the lateral and third ventricle with an irregular
ventricular enlargement [[Figure 3]]. At the current presentation, the patient was in altered sensorium for 5 days and
on examination, he was drowsy and spontaneously moving all the four limbs equally
with Glasgow Coma Scale E4V2M5; his bilateral pupils were reacting to light and fundus
examination showed bilateral papilledema. A NCCT brain showed obstructive hydrocephalus
along with previous lesions [[Figure 4]]. The patient was planned for urgent craniotomy and decompression. Right pterional
craniotomy and tumor decompression was done. The lesion was heterogeneous in the consistency,
mildly vascular, suckable, infiltrating into the 3rd ventricle and frontal horn, encasing
the anterior cerebral artery without any plane of cleavage. The histopathological
examination was suggestive of morphological features of Germinoma with immunohistochemistry
features were also characteristic of Germinoma with oct3 and SALL4 positivity [[Figure 5]].
Figure 1: Magnetic resonance imaging brain showing prominent nodular hyperintensities around
the left occipital horn, bilateral frontal horns, right thalamic region, and altered
signal intensities in the corpus callosum
Figure 2: Progression of lesion with diffuse involvement of the left occipital horn, third
ventricle, and bilateral frontal horn with appearance of new solid-cystic lesions
around the frontal horn and pineal region. Magnetic resonance spectroscopy showing
lipid peak
Figure 3: Noncontrast computed tomography scan of brain showing significant diffuse nodular
densities around the lateral and third ventricle with irregular ventricular enlargement
Figure 4: Noncontrast computed tomography brain showing obstructive hydrocephalus along with
previous lesions
Figure 5: (a) H and E, *20, showing tumor cells having large vesicular nuclei and prominent
eosinophilic nuclei, admixed are numerous mature lymphocytes. (b) H and E, xio, granuloma
with cuff of lymphocytes at one end. (c) Immunohistochemistry for oct3 showing strong
nuclear positivity, characteristic of germinoma. (d) Immunohistochemistry for SALL4
showing strong nuclear positivity, characteristic of germinoma
Discussion
Germinomas are the most common intracranial GCTs. The most common presentation of
these tumors is due to infiltration and mass effect over the surrounding structures
such as aqueduct causing obstructive hydrocephalus, chiasma causing visual deterioration,
hypothalamic–hypophyseal dysfunction, or tectal infiltration causing features of Parinaud's
syndrome, but in our patient, the presentation was atypical. The radiological features
were also unusual, not favoring any particular lesion such as neoplastic, inflammatory,
and infectious etiologies. In this case, considering the patient's age and clinicoradiological
features, meningitis of tubercular etiology must have been kept as a primary diagnosis
with lymphoma as a second possibility. The characteristic neuroimaging features of
tubercular meningitis include leptomeningeal and basal cisternal enhancement with
thick basilar exudates, especially in the interpeduncular fossa, prepontine cistern,
ambient cistern, suprasellar cistern, and Sylvian fissures, presenting as confluent
enhancing lesions. On MRI, ependymitis presents with a thickened and enhanced ependymal
lining, dilated ventricles, and presence of debris with irregular margins in the dependent
portions of the ventricles. Periventricular infarcts are also frequently seen. Lymphoma
is generally a homogeneous lesion, whereas germinoma is more often heterogeneous with
microcystic areas and the surrounding edema is generally less marked in lymphoma than
other intracranial tumors with low or no mass effect. Although ependymal and sub-arachnoidal
extension/dissemination are frequent in central nervous system lymphomas, they can
be seen in other tumors such as germinoma, high-grade astrocytoma, pineoblastoma,
and metastasis. In this case, the Germinoma was not considered as a differential diagnosis
due to atypical radiological features, non-availability of tumor markers, and very
few reports in the literature of Germinoma with diffuse subependymal dissemination.
The significant progressive degree of ependymitis and subarachnoid spread could have
been responsible for the mistaken diagnosis of tubercular meningitis clinicoradiologically.
The leptomeningeal dissemination can be diagnosed by a single CSF study, but unfortunately,
it was not available. In the available literature, very few cases have been reported
either as a case of periventricular germinoma mostly involving ventricles only, or
a midline lesion with the involvement of lateral ventricle, or a midline lesion with
the involvement of one or more ventricle.[[4]],[[7]],[[8]] In Indian literature, only one reported case may be found, of an intracranial germinoma
with subarachnoid spread.[[9]]
Conclusion
This case represents an unusual rare presentation of primary intracranial germinoma,
which must be kept in diagnosis with diffuse subependymal spread, and CSF analysis
must be done for the diagnosis of subarachnoid dissemination, as positive CSF cytology
may be considered sufficient for initiating radiation therapy for such curable radiosensitive
tumor even without the invasive tissue diagnosis.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms.
In the form, the legal guardian has given his consent for images and other clinical
information to be reported in the journal. The guardian understands that names and
initials will not be published and due efforts will be made to conceal identity, but
anonymity cannot be guaranteed.
