Granulomatous tissue response in germinoma, a diagnostic pitfall in endoscopic biopsy

Multiple ectopic germinomas presenting as focal dystonia of fingers: a case report and literature review

BACKGROUND

Intracranial primary germinomas predominantly develop on or near the midline structure in children and young adults and are diagnosed by brain imaging and biopsy. However, if brain imaging and pathology show unusual findings, it becomes difficult to make an accurate diagnosis.

CASE REPORT

Herein, we report the case of a 14-year-old boy who presented with focal dystonia of the fingers as an initial symptom. Magnetic resonance imaging of the brain showed multifocal heterogeneous lesions with solid and cystic components involving the right frontal lobe, corpus callosum, left basal ganglia, and left corona radiata. A stereotactic biopsy of the right frontal lesion revealed several granulomatous areas with abundant inflammatory cells. After immunohistochemical staining, the patient was diagnosed with germinoma and treated with chemoradiotherapy according to the Korean Society for Pediatric Neuro-Oncology protocol. The patient has been in complete remission for five years.

CONCLUSION

Germinomas can develop in intracranial off-midline structures, with unusual clinical, radiological, and pathological presentations. It is important to include intracranial germinomas in the differential diagnosis of infiltrative parenchymal tumors, especially in children.

Diagnosis and Management of Pineal Germinoma: From Eye to Brain

Pineal germinomas can be very complex in terms of presentation, diagnosis, and management. This review attempts to simplify this complexity in an organized manner, addressing the anatomic relationships that provide the basis for the uniqueness of pineal germinoma. Ocular findings and signs and symptoms of elevated intracranial pressure are the keys to suspecting the diagnosis and obtaining the necessary imaging and cerebrospinal fluid studies. Other symptoms can suggest spread beyond the pineal region. Surgery may only be needed to obtain tissue for a definitive diagnosis, as germinoma is highly responsive to chemotherapy and focused radiation therapy. Hydrocephalus, usually related to tumor obstruction of the cerebral aqueduct, may also need to be addressed. Outcome for pineal germinoma is usually excellent, but relapse can occur and may require additional intervention. These issues are detailed in this review.

Intracranial Germinoma Masquerading as Secondary Granulomatous Hypophysitis: A Case Report and Review of Literature

Germinomas are highly immunogenic tumors eliciting a strong peri-tumoral immune response that can spillover into the surrounding healthy tissues. This phenomenon can also occur in intracranial germinomas, manifesting as secondary hypophysitis. Herein, we report a case of 12-year-old-girl presenting with polyuria and polydispsia. She had central diabetes insipidus (CDI) and panhypopituitarism. Imaging revealed a sellar-suprasellar mass with infundibular stalk thickening. Transphenoidal biopsy revealed epithelioid granulomas with immunostaining negative for germinomatous cells. Other causes of hypophysitis were ruled out. Accordingly, she was diagnosed as primary granulomatous hypophysitis and treated with high-dose corticosteroids. Three years later she again presented with headache, vomiting and diminution of vision. Imaging showed a heterogeneous, solid-cystic peripheral rim-enhancing lesion at the same location with involvement of hypothalamus, ependyma and pineal gland. Cerebrospinal fluid beta-human chorionic gonadotropin was markedly elevated, confirming the diagnosis of an intracranial germ cell tumor. She was started on chemotherapy; however, she succumbed to febrile neutropenia. We performed a literature search and found 18 anecdotal cases of secondary hypophysitis associated with intracranial germinomas. There was a slight male preponderance (male:female 5:4). Two-thirds of the cases were below 18 years of age. Polyuria was the most common presenting manifestation (83%). CDI and panhypopituitarism were seen in 89 and 78% cases, respectively. Imaging evidence of pituitary stalk thickening was seen in 12 cases (67%), while pituitary enlargement and/or sellar mass were reported in 11 cases (61%). Pineal involvement was extremely rare, being reported in only 1 case, implying the predilection of suprasellar (rather than pineal) germinomas in causing secondary hypophysitis. Histologically, 82% had lymphocytic hypophysitis, while 18% had granulomatous hypophysitis. Initially, the diagnosis of germinoma was missed in 60% of the cases who were wrongly treated with corticosteroids. To conclude, physicians should make it a dictum that all children and adolescents presenting with CDI and pituitary stalk thickening should be rigorously screened for an underlying intracranial germinoma before labeling them as primary hypophysitis.

Granulomatous Response in Intracranial Germinomas: Diagnostic Problems

Intracranial germinomas are rare and account for <0.5% of primary intracranial tumors. In contrast to the gonadal germinomas, these do not show granulomatous response within the tumor. In rare cases, the granulomatous component may obscure the tumor proper and lead to diagnostic difficulties/dilemmas. We report a case of suprasellar germinoma in a 17-year-old boy which showed granulomatous response. We discuss the differentials to be considered in such a scenario and discuss the utility of squash cytology and immunohistochemistry in these lesions.

Primary Germinoma Originating from the Insular Lobe: A Case Report and Review of the Literature

BACKGROUND

Primary intracranial germinomas occurring in the cerebral hemisphere are extremely rare, with only a few reported cases in the literature. We describe an unusual case of a primary germinoma that developed in the insular lobe, with little involvement in the basal frontal lobe.

CASE DESCRIPTION

A 19-year-old man presented with headache and vomiting. Magnetic resonance imaging showed a solitary, ring-like enhanced lesion in the left hemisphere, and a preliminary diagnosis of glioma was made. Surgery was performed, and the diagnosis of germinoma was made based on the histopathologic results.

CONCLUSIONS

The causes of ectopic germinomas of the midline structures of the brain are still unclear, but the theory of misplacement may partially clarify this phenomenon. Reflecting a lack of definitive management guidelines for atypical germinoma, the present patient was treated with focal radiotherapy around the lesion after surgery and achieved remission by 34 months postoperatively.

Germinoma Mimicking Tumefactive Demyelinating Disease in Pediatric Patients

Cases of intracranial germinoma with granulomatous reaction are rare, so a pathological diagnosis of this disease is difficult. In this report, we describe the case of a 13-year-old boy with a bilateral thalamic germinoma which initially mimicked tumefactive demyelinating disease with inflammation, based on the clinical symptoms, imaging results and histology of a biopsy specimen obtained endoscopically. Upon examination of the cerebrospinal fluid, oligoclonal bands were detected. Although his symptoms and radiological findings improved following steroid pulse treatment, they worsened dramatically almost 1 year after the first surgery and even after an additional steroid pulse treatment. Prompted by the clinical course, a second biopsy was performed, and a pathological examination of the specimen showed a two-cell pattern. The diagnosis was changed to intracranial germinoma. After chemotherapeutic treatment with etoposide and cisplatin, the patient's symptoms and radiological findings dramatically improved. We conclude that it is very challenging to distinguish germinomas with a granulomatous reaction due to other inflammatory diseases, especially when only small specimens can be obtained. Stereotactic or endoscopic biopsies should be performed using samples from several different points even if the lesions are associated with eloquent brain regions.

Expression of Kit and Etv1 in restricted brain regions supports a brain-cell progenitor as an origin for cranial germinomas

Mismigrating germ-cell progenitors have historically been accepted as the cell of origin for central nervous system (CNS) germinomas. However, an alternative hypothesis suggests that CNS germinomas arise from a brain-cell progenitor. Germinomas often acquire Kit signaling pathway mutations, and there is evidence for an oncogenic relationship between KIT and the ETV1 transcription factor. KIT appears to be necessary to stabilize ETV1, and ETV1 then activates oncogenesis-associated genes. ETV1 expression is not increased by KIT, so ETV1 already needs to be expressed in order for KIT to have an oncogenic function. Therefore, if brain-cell progenitors are the cell of origin for germinomas, those cells would already need to coexpress ETV1 and KIT. We examined Kit and Etv1 in situ hybridization data from the Allen Brain Atlas, for mouse brain tissue at various stages of development. Both Kit and Etv1 were expressed in the regions where germinomas most commonly arise, and in the medulla oblongata. All human cases of germinomas correlated to the regions where ETV1 and KIT are coexpressed. We therefore postulate that germinomas in the brain share a similar mechanism with other KIT-driven cancers, which supports the hypothesis that germinomas arise from a brain-cell progenitor.

Endoscopic biopsy of brain tumors: Does the technique matter?

Background:

Endoscopic biopsy of brain tumors is an important part of the armamentarium of management of intra- and periventricular tumors that is generally considered an acceptable and, in some situations, a preferred method for tissue sampling. The diagnostic yield of the procedure has been variably reported. Technical aspects of the procedure should undoubtedly reflect on its success rate and accuracy. Such impact on diagnostic yield of endoscopic brain biopsy is infrequently discussed in the literature.

Methods:

A search of the medical literature was conducted for publications on endoscopic brain biopsy. These reports were analyzed regarding the various technical aspects.

Results:

In the 43 publications analyzed, lenscopes were exclusively used in 22 reports and a tissue diagnosis was possible in 362 out of 387 endoscopic biopsies with a diagnostic yield of 93.54%. Only fiberscopes were used in 8 reports and a tissue diagnosis was possible in 100 out of 132 endoscopic biopsies with a diagnostic yield of 75.76%. The diagnostic yield in the mixed and unspecified groups was 88.95 and 88.04%, respectively. Very few details on the histopathological methods and tumor molecular genetics could be found.

Conclusion:

Endoscopic biopsy of brain tumors has a higher diagnostic yield when lenscopes are used. Neuronavigation seems to add to the diagnostic accuracy of the procedure. Studies detailing molecular genetic features of biopsied tumors are necessary in the future.

[Intracranial germinoma masquerading as a granulomatous inflammation, diagnostic failure after brain biopsy]

We report the case of a 33-year-old man with diplopia, sleepiness, and paresthesia of the left upper limb that were slowly progressive. On admission, he presented with restriction in the vertical movement of the eyes and abduction of the right eye, and horizontal and convergence nystagmus. Slight weakness of the left upper limb, bilateral Babinski sign, and truncal ataxia were also noted. Cerebral magnetic resonance imaging was performed, and gadolinium-enhanced T1-weighted imaging revealed a mass lesion that involved the diencephalon and the corpus callosum, which was invariably enhanced. Specimens obtained using a brain biopsy showed epithelioid granuloma with the presence of foreign body giant cells and lymphocytic infiltration. Prednisolone was administrated because we suspected neurosarcoidosis, but the clinical symptoms worsened with the enlargement of the lesion. A re-evaluation of the biopsy specimens using immunohistochemistry revealed tumor cells of germinoma that were scattered among the lymphocytes and positive for periodic acid-Schiff staining, placental alkaline phosphatase, and c-kit. A combination of chemotherapy and radiation resulted in clinical improvement and marked reduction of the mass lesion in size. We concluded that the possibility of germinoma should be considered in case granulomatous inflammation is observed in brain biopsy specimens.

Unusual behaviour of a pineal germinoma mimicking neurosarcoidosis and metastasising along the endoscopic route

A previously healthy man underwent endoscopic biopsy for a suspected pineal germinoma. Histology and immunohistochemistry did not confirm the preoperative diagnosis, and neurosarcoidosis was hypothesised because of the presence of granulomatous reaction. The patient remained in good health for 3 years and was still asymptomatic when a control MRI showed metastasis implantation along the endoscopic route. A redobiopsy provided the diagnosis of germinoma, but was complicated by severe ventricular haemorrhage requiring emergency clot excision. Postoperative clinical conditions were so severe that the treatment of germinoma was postponed. Three months later, repeated MRI showed tumour progression. Chemotherapy promoted good tumour regression so that the treatment was completed by radiation therapy. The tumour completely disappeared on MRI, but the patient remained severely disabled because of the haemorrhage.

Neurohypophyseal germinoma with abundant fibrous tissue

We report an unusual case of neurohypophyseal germinoma with abundant fibrous tissue and clival invasion that was initially misdiagnosed as lymphocytic hypophysitis. A 40-year-old woman presented with diabetes insipidus and panhypopituitarism after delivering her second son and which lasted for 4 years. Magnetic resonance imaging showed the intrasellar mass extending to the suprasellar region with enlarged pituitary stalk. The mass was heterogeneously enhanced and invaded the clivus. Biopsy of the intrasellar mass was performed via the trans-sphenoidal route, and histological examination revealed marked fibrous tissue and infiltration of lymphocytes, with no evidence of tumor cells. Lymphocytic hypophysitis was the initial diagnosis, and corticosteroid therapy was begun. Despite intensive treatment, the lesion enlarged and clinical symptoms worsened 2 weeks after surgery. Subtotal removal of the mass was performed, and a second histological examination revealed typical findings of the germinoma. Subsequently, the patient underwent chemoradiotherapy, and complete remission was achieved. Histological diagnosis is sometimes incorrect in fibrous tumors at the sellar region, and biopsy from several points is strongly recommended for this entity.

Is biopsy needed to guide management for all patients with presumed intracranial ectopic germinomas

Intracranial germinomas may arise in sites besides pineal and suprasellar regions, which we call intracranial ectopic germinomas (IEGs). In this article we evaluated the rationality of radiotherapy in IEGs when histopathological evidence could not be obtained. Criteria for initiating experimental radiotherapy in patients with clinically presumed IEGs was established according to the reports published in this field and the experience gained from our five histopathologically verified IEG patients. When patients suspected to have IEGs met the criteria, radiotherapy following standard protocol was performed. Strict criteria was also employed to evaluate the effectiveness of radiotherapy after completion of initial experimental dose of radiation and to determine whether total dose of radiation should be delivered. Seven patients clinically suspected to have IEGs met the criteria for radiotherapy. Radiotherapy was evaluated as effective in six patients immediately after completion of initial experimental dose of radiation and the remaining dose was delivered. However, effectiveness of initial experimental radiotherapy was not testified until 2 months later in the other one patient. Total dose of radiation was completed and satisfactory results achieved in all seven patients. In conclusion, the histopathological verification is not mandatory for radiotherapy in patients with IEGs when histopathological evidence can not be obtained. Strict criteria should be followed to enroll patients to undergo experimental radiotherapy.