Pathological features of intracranial germinomas with reference to fibrous tissue and granulomatous change

Intracranial Germinomas: Diagnosis, Pathogenesis, Clinical Presentation, and Management

PURPOSE OF REVIEW

Intracranial germinomas constitute a rare brain tumor entity of unknown etiology, characterized by unique histopathology and molecular biology. In this manuscript, we review the literature focusing on the epidemiology, histopathology with molecular biology, clinical presentation with emphasis on tumor location, diagnostic workup, and current treatment strategies with related clinical outcomes of intracranial germinomas.

RECENT FINDINGS

Although the optimal treatment strategy remains a matter of debate, intracranial germinomas respond well to radiotherapy, chemotherapy, or a combination of both and are characterized by very high cure and survival rates. It is well-known that early discrimination of germinomas from other intracranial neoplasms facilitates the timely initiation of appropriate treatment, thereby contributing to the reduction of morbidity as well as mortality. Ongoing research will need to be directed towards discovering and refining reliable parameters for early diagnosis and evaluation of prognosis in patients with intracranial germinomas.

Brain and Spinal Tumors Originating from the Germ Line Cells

Primary central nervous system germ cell tumors (CNS GCTs) are part of the GCTs in children and adults. This tumor entity presents with geographic variation, age, and sex predilection. There are two age peaks of incidence distribution at the first few months of life and in adolescence. CNS GCTs are heterogeneous in histopathological subtypes, locations, and tumor marker (AFP, β-hCG) secretions. In the WHO CNS tumor classification, GCTS are classified as germinoma and nongerminomatous GCT (NGGCT) with different subtypes (including teratoma). Excluding mature teratoma, the remaining NGGCTs are malignant (NGMGCT). In teratoma, growing teratoma syndrome and teratoma with somatic-type malignancy should be highlighted. The common intracranial locations are pineal region, neurohypophysis (NH), bifocal pineal-NH, basal ganglia, and cerebral ventricle. Above 50% of intracranial GCTs (IGCTs) present obstructive hydrocephalus. Spinal tumors are rare. Age, locations, hydrocephalus, and serum/CSF titer of β-hCG correlate with clinical manifestations. Delayed diagnosis is common in tumors arising in neurohypophysis, bifocal, and basal ganglia resulting in the increasing of physical dysfunction and hormonal deficits. Staging work-up includes CSF cytology for tumor cells and contrast-enhanced MRI of brain and spine for macroscopic metastasis before treatment commences. The therapeutic approach of CNS GCTs integrates locations, histopathology, staging, tumor marker level, and therapeutic classification. Treatment strategies include surgical biopsy/excision, chemotherapy, radiotherapy (single or combination). Secreting tumors with consistent imaging may not require histopathological diagnosis. Primary germinomas are highly radiosensitive and the therapeutic aim is to maintain high survival rate using optimal radiotherapy regimen with/without chemotherapy combination. Primary NGNGCTs are less radiosensitive. The therapeutic aim is to increase survival utilizing more intensive chemotherapy and radiotherapy. The negative prognostic factors are residue disease at the end of treatment and serum or CSF AFP level >1000 ng/mL at diagnosis. In refractory or recurrent NMGGCTs, besides high-dose chemotherapy, new therapy is necessary. Molecular profiling and analysis help for translational research. Survivors of pediatric brain tumors frequently experience cancer-related cognitive dysfunction, physical disability, pituitary hormone deficiency, and other CNS complications after cranial radiotherapy. Continuous surveillance and assessment may lead to improvements in treatment protocols, transdisciplinary interventions, after-treatment rehabilitation, and quality of life.

Primary midbrain germinoma relapse-free for 5 years: A case report

Background

The biology and clinical course of intracranial germinomas differ as per their location of occurrence. Germinoma of the primary midbrain is particularly rare, and its clinical features, treatment strategies, and long-term prognosis remain uncertain.

Case Description

A 39-year-old man who had been diagnosed with midbrain germinoma by open biopsy through the occipital transtentorial approach had undergone chemoradiotherapy and achieved 5 years with no recurrence.

Conclusion

Germinomas should be considered as a differential diagnosis for adolescents and young adult men with mesencephalic tumors, and reliable sampling followed by chemoradiotherapy must be performed.

Very Unusual Sellar/Suprasellar Region Masses: A Review

The cause of sellar region masses in large retrospective series is overwhelmingly pituitary adenomas (84.6%), followed by craniopharyngiomas (3.2%), cystic nonneoplastic lesions (2.8%), inflammatory lesions (1.1%), meningiomas (0.94%), metastases (0.6%), and chordomas (0.5%) (1). While other rare lesions were also identified (collectively 6.0%), single unusual entities in the above-cited series numbered <1-2 examples each out of the 4122 cases, underscoring their rarity. We searched our joint files for rare, often singular, sellar/suprasellar masses that we had encountered over the past several decades in our own specialty, tertiary care specialty pituitary center practices. Cases for this review were subjectively selected for their challenging clinical and/or histological features as well as teaching value based on the senior authors' (MBSL, BKD) collective experience with over 7000 examples. We excluded entities deemed to be already well-appreciated by neuropathologists such as mixed adenoma-gangliocytoma, posterior pituitary tumors, metastases, and hypophysitis. We identified examples that, in our judgment, were sufficiently unusual enough to warrant further reporting. Herein, we present 3 diffuse large cell B cell pituitary lymphomas confined to the sellar region with first presentation at that site, 2 sarcomas primary to sella in nonirradiated patients, and 1 case each of granulomatosis with polyangiitis and neurosarcoidosis with first presentations as a sellar/suprasellar mass. Other cases included 1 of chronic lymphocytic leukemia within a gonadotroph adenoma and 1 of ectopic nerve fascicles embedded within a somatotroph adenoma, neither of which impacted patient care. Our objective was to share these examples and review the relevant literature.

Bilateral optic neuropathy with central diabetes insipidus in a child

Central nervous system germ cell tumors are rare and they occur in the first two decades of life.^[1] Optic nerve germinomas can sometimes mimic optic nerve inflammation.^[2] In this case report, we discuss an 11-year-old girl who presented with features of presumed bilateral optic neuritis and developed polyuria and polydipsia, subsequently she was diagnosed to have infiltrative etiology. Her clinical and radiological presentations were initially consistent with inflammatory optic neuropathy. Poor visual recovery to steroid therapy and progressive visual loss warranted the need for optic nerve biopsy which revealed germinoma.

Human chorionic gonadotropin is expressed virtually in all intracranial germ cell tumors

Human chorionic gonadotropin (hCG) production has been utilized as a diagnostic marker for germinoma with syncytiotrophoblastic giant cells (STGC) and choriocarcinoma. Elevated hCG in germinoma is considered to predict less favorable prognosis, and an intensive treatment strategy may accordingly be applied. However, there is some evidence that any germinoma may produce hCG to varying extent. We investigated mRNA expression of the hCG β subunit (hCGβ) using real time quantitative polymerase chain reaction in 94 germ cell tumors (GCTs). Most (93.3 %) GCTs showed higher expression levels compared with that of normal brain tissue (1.09 × 10(0)-1.40 × 10(5) fold). The expression was the highest in GCTs which harbor choriocarcinoma or STGC components. The expression level of hCGβ in germinoma was highly variable (1.09 × 10(0)-5.88 × 10(4) fold) in linear but not bimodal distribution. hCG concentrations in serum and CSF correlated with gene expression, especially when GCTs with single histological component were analyzed separately. The expression was not significantly associated with recurrence in pure germinoma. These results suggest that the serum/CSF hCG levels may need to be interpreted with caution as most GCTs appear to have the capacity of producing hCG irrespective of their histology. The clinical significance of ubiquitous hCG expression in GCTs needs further investigation.

Histopathology of pineal germ cell tumors

Germ cell tumors (GCTs) classically occur in gonads. However, they are the most frequent neoplasms in the pineal region. The pineal location of GCTs may be caused by the neoplastic transformation of a primordial germ cell that has mismigrated. The World Health Organization (WHO) recognizes 5 histological types of intracranial GCTs: germinoma and non-germinomatous tumors including embryonal carcinoma, yolk sac tumor, choriocarcinoma and mature or immature teratoma. Germinomas and teratomas are frequently encountered as pure tumors whereas the other types are mostly part of mixed GCTs. In this situation, the neuropathologist has to be able to identify each component of a GCT. When diagnosis is difficult, use of recent immunohistochemical markers such as OCT(octamer-binding transcription factor)3/4, Glypican 3, SALL(sal-like protein)4 may be required. OCT3/4 is helpful in the diagnosis of germinomas, Glypican 3 in the diagnosis of yolk sac tumors and SALL4 in the diagnosis of the germ cell nature of an intracranial tumor. When the germ cell nature of a pineal tumor is doubtful, the finding of an isochromosome 12p suggests the diagnosis of GCT. The final pathological report should always be confronted with the clinical data, especially the serum or cerebrospinal fluid levels of β-human chorionic gonadotropin (HCG) and alpha-fetoprotein.

Role of stereotactic biopsy in histological diagnosis of multiple brain lesions

Background and Aim:

The current advances in diagnostic and therapeutic modalities and increasing in survival of patients with systemic diseases and immunosuppressive cases have caused to increasing frequency and variety of Central Nervous System neuropathologic processes indicating the necessary need for accurate localization of space-occupying lesions by cytology and histology. This study was aimed to evaluate the usefulness and safety of stereotactic biopsy in histological diagnosis of such lesions.

Materials and Methods:

Of 2081 patients underwent stereotactic biopsy of brain lesions using Riechert-Mundinger system, 158 had multifocal brain lesions, and were enrolled.

Results:

The ages of studied cases were ranged from 2 years to 75 years (Mean age: 41.3 year), 114 were male and 44 were females. Incidence of histopathologic diagnosis of multifocal brain lesions included Astrocytoma grade II (41.3%), Astrocytoma grade I (12.9%), glioblastoma multiform (11.1%), Astrocytoma grade III (10.2%), malignant lymphoma (10.2%), metastasis (4.6%), pilocytic Astrocytoma (2.7%), abscess (2.7%), craniopharyngioma (1.8%) vascular malformations (0.9%), and tuberculosis (0.9%). Mortality due to operation is none.

Conclusions:

Histopathologic diagnosis of multiple brain lesions is necessary for decision of appropriate management and stereotactic biopsy of brain lesion is a useful and safe method for histological diagnosis.

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.

Histological Features of Intracranial Germinomas Not Disappearing Immediately After Radiotherapy

The histological features of germinomas were investigated to differentiate tumors which completely disappear immediately after irradiation and those that persist. Eighteen previously untreated patients underwent germinoma biopsy and irradiation or combined irradiation and chemotherapy. Four tumors were located only in the pineal gland, eight in the suprasellar region, two in multiple locations, one in the basal ganglia, and three in other regions. Histologically, the germinomas could be divided into type A found in 13 cases which consisted mainly of large neoplastic cells and small lymphocytes, the so-called two-cell pattern, and type B found in five cases which consisted predominantly of fibrous tissue and granulomatous reaction containing occasional neoplastic cells. Follow-up computed tomography or magnetic resonance imaging showed the enhanced mass lesion disappeared in all cases of type A germinomas within 1 month after treatment, but persisted in all cases of type B germinomas for at least 1 month. Type B tumors required up to 12 months to show complete radiographic resolution. Persistent germinomas consisted predominantly of fibrous tissue and granulomatous reaction containing occasional neoplastic cells.