Magnetic resonance imaging of neurohypophyseal germinomas

Imaging in malignant germ cell tumors involving the hypothalamo-neurohypophyseal axis: the evaluation of the posterior pituitary bright spot is essential

PURPOSE

Malignant intracranial germ cell tumors (GCTs) are rare diseases in Western countries. They arise in midline structures and diagnosis is often delayed. We evaluated imaging characteristics and early tumor signs of suprasellar and bifocal GCT on MRI.

METHODS

Patients with the diagnosis of a germinoma or non-germinomatous GCT (NGGCT) who received non-contrast sagittal T1WI on MRI pre-therapy were included. Loss of the posterior pituitary bright spot (PPBS), the expansion and size of the tumor, and the expansion and infiltration of surrounding structures were evaluated. Group comparison for histologies and localizations was performed.

RESULTS

A total of 102 GCT patients (median age at diagnosis 12.3 years, range 4.4-33.8; 57 males; 67 in suprasellar localization) were enrolled in the study. In the suprasellar cohort, NGGCTs (n = 20) were noticeably larger than germinomas (n = 47; p < .001). Each tumor showed involvement of the posterior lobe or pituitary stalk. A PPBS loss (total n = 98) was observed for each localization and entity in more than 90% and was related to diabetes insipidus. Osseous infiltration was observed exclusively in suprasellar GCT (significantly more frequent in NGGCT; p = .004). Time between the first MRI and therapy start was significantly longer in the suprasellar cohort (p = .005), with an even greater delay in germinoma compared to NGGCT (p = .002). The longest interval to treatment had circumscribed suprasellar germinomas (median 312 days).

CONCLUSION

A loss of the PPBS is a hint of tumor origin revealing small tumors in the neurohypophysis. Using this sign in children with diabetes insipidus avoids a delay in diagnosis.

Neuroimaging of hypophysitis: etiologies and imaging mimics

Hypophysitis is an inflammatory disease affecting the pituitary gland. Hypophysitis can be classified into multiple types depending on the mechanisms (primary or secondary), histology (lymphocytic, granulomatous, xanthomatous, plasmacytic/IgG4 related, necrotizing, or mixed), and anatomy (adenohypophysitis, infundibulo-neurohypophysitis, or panhypophysitis). An appropriate diagnosis is vital for managing these potentially life-threatening conditions. However, physiological morphological alterations, remnants, and neoplastic and non-neoplastic lesions may masquerade as hypophysitis, both clinically and radiologically. Neuroimaging, as well as imaging findings of other sites of the body, plays a pivotal role in diagnosis. In this article, we will review the types of hypophysitis and summarize clinical and imaging features of both hypophysitis and its mimickers.

Imaging of pituitary tumors: an update with the 5th WHO Classifications-part 2. Neoplasms other than PitNET and tumor-mimicking lesions

Many types of tumors can develop in the pituitary gland. In the recently revised 5th editions of the World Health Organization (WHO) classifications (2021 WHO Classification of Central Nervous System Tumors and the 2022 WHO Classification of Endocrine and Neuroendocrine Tumors), various changes have been made to the tumors other than pituitary neuroendocrine tumor (PitNET)/pituitary adenoma, as well as PitNET. Adamantinomatous craniopharyngioma and papillary craniopharyngioma are now considered separate tumors in the 5th edition of the WHO classification. Tumors positive for thyroid transcription factor 1, a marker of posterior pituitary cells, are now grouped together in the pituicyte tumor family in the 5th edition of the WHO classification of Endocrine and Neuroendocrine Tumors. Poorly differentiated chordoma is newly listed in the 5th edition of the WHO Classification of Endocrine and Neuroendocrine Tumors. In this paper, we present the latest WHO classification of pituitary tumors (adamantinomatous craniopharyngioma, papillary craniopharyngioma, pituitary blastoma, pituicyte tumor family, tumors of pituitary origin other than those of the pituicyte tumor family, germinoma, meningioma, chordoma, metastatic tumors, lymphoma, and pituitary incidentaloma), review diseases requiring differentiation from tumors (pituitary abscess, hypophysitis, pituitary hyperplasia, Rathke's cleft cyst, arachnoid cyst, and aneurysm), and discuss diagnoses based on imaging findings.

Differentiation between Germinoma and Craniopharyngioma Using Radiomics-Based Machine Learning

For the tumors located in the anterior skull base, germinoma and craniopharyngioma (CP) are unusual types with similar clinical manifestations and imaging features. The difference in treatment strategies and outcomes of patients highlights the importance of making an accurate preoperative diagnosis. This retrospective study enrolled 107 patients diagnosed with germinoma (n = 44) and CP (n = 63). The region of interest (ROI) was drawn independently by two researchers. Radiomic features were extracted from contrast-enhanced T1WI and T2WI sequences. Here, we established the diagnosis models with a combination of three selection methods, as well as three classifiers. After training the models, their performances were evaluated on the independent validation cohort and compared based on the index of the area under the receiver operating characteristic curve (AUC) in the validation cohort. Nine models were established and compared to find the optimal one defined with the highest AUC in the validation cohort. For the models applied in the contrast-enhanced T1WI images, RF_S + RF_C and LASSO + LDA were observed to be the optimal models with AUCs of 0.91. For the models applied in the T2WI images, DC + LDA and LASSO + LDA were observed to be the optimal models with AUCs of 0.88. The evidence of this study indicated that radiomics-based machine learning could be potentially considered as the radiological method in the presurgical differential diagnosis of germinoma and CP with a reliable diagnostic performance.

Up-To-Date Magnetic Resonance Imaging Findings for the Diagnosis of Hypothalamic and Pituitary Tumors

Magnetic resonance imaging (MRI) is the preferred imaging technique for the sellar and parasellar regions. In this review article, we report our clinical experience with MRI for hypothalamic and pituitary lesions, such as pituitary adenomas, craniopharyngiomas, Rathke cleft cysts, germinoma, and hypophysitis with reference to the histopathological findings through a review of the literature. Our previous study indicated that three dimensional-spoiled gradient echo sequence is a more suitable sequence for evaluating sellar lesions on postcontrast T1 weighted image (WI). This image demonstrates the defined relationship between the tumor and its surroundings, such as the normal pituitary gland, cavernous sinus, and optic pathway. We demonstrated the characteristic MRI findings of functioning pituitary adenoma. In growth hormone-producing adenoma, signal intensity on T2WI is important to differentiate densely from sparsely granulated somatotroph adenomas. In prolactin-producing pituitary adenomas, distinct hypointense areas in early phase on T2WI, possibly owning to diffuse hemorrhage, indicate pronounced regressions of invasive macroprolactinomas during cabergoline therapy. The two histopathological subtypes, adamantinomatous and squamous papillary craniopharyngioma, differ in genesis. Calcified tumors are mostly adamantinomatous type. On MRI, these lesions have a heterogenous appearance with a solid portion and cystic components. The solid portions and cyst wall enhance heterogeneously. Although cyst fluid of Rathke cleft cysts show variable intensities on MRI, intracystic waxy nodule can be hypointense on T2WI. The enhancing cyst wall may contain the squamous metaplasia. Cystic lesions of the sellar and parasellar areas may be difficult to differentiate on a clinical, imaging, or even histopathological basis.

Pediatric Suprasellar Germ Cell Tumors: A Clinical and Radiographic Review of Solitary vs. Bifocal Tumors and Its Therapeutic Implications

Suprasellar germ cell tumors (S-GCTs) are rare, presenting in either solitary or multifocal fashion. In this study, we retrospectively examine 22 solitary S-GCTs and 20 bifocal germ cell tumors (GCTs) over a 30-year period and demonstrate clinical, radiographic, and prognostic differences between the two groups with therapeutic implications. Compared to S-GCTs, bifocal tumors were almost exclusively male, exhibited higher rate of metastasis, and had worse rates of progression free and overall survival trending toward significance. We also introduce a novel magnetic resonance (MR) imaging classification of suprasellar GCT into five types: a IIIrd ventricle floor tumor extending dorsally with or without an identifiable pituitary stalk (Type Ia, Ib), ventrally (Type III), in both directions (Type II), small lesions at the IIIrd ventricle floor extending to the stalk (Type IV), and tumor localized in the stalk (Type V). S-GCTs almost uniformly presented as Type I-III, while most bifocal GCTs were Type IV with a larger pineal mass. These differences are significant as bifocal GCTs representing concurrent primaries or subependymal extension may be treated with whole ventricle radiation, while cerebrospinal fluid (CSF)-borne metastases warrant craniospinal irradiation (CSI). Although further study is necessary, we recommend CSI for bifocal GCTs exhibiting high-risk features such as metastasis or non-germinomatous germ cell tumor histology.

Bifocal germinomas in the pineal region and hypothalamo-neurohypophyseal axis: Primary or metastasis?

Whether bifocal germinomas (BFGs) synchronously presenting within the pineal region and the hypothalamo-neurohypophyseal axis (HNA) are primary germinomas of dual-origin remains to be elucidated. We analyzed MRI images and clinical features of 95 neurohypophyseal germinomas and 21 BFG patients and developed a tentative definition of the BFGs. We found dual-primary BFGs (true BFGs) do exist. The fundamental difference between primary and metastatic HNA germinomas was the direction of tumor growth. For a true BFG, the primary HNA tumor grew from the neurohypophysis toward the hypothalamus and almost invaded the whole pituitary stalk. For a false BFG (primary pineal germinoma with HNA metastasis), the metastatic HNA tumor first appeared at the third ventricular floor (TVF), grew toward the neurohypophysis, but commonly did not invade the inferior pituitary stalk. Compared to false BFGs, true BFGs commonly had diabetes insipidus as the first symptom, dysfunction of the anterior pituitary, no high-intensity MRI signal at the posterior pituitary, a larger extension of the HNA tumor, and fewer numbers of remote lesions from cerebrospinal fluid seeding. Accordingly, 12.8% (12/96) of our germinoma patients had true BFGs, and of these, 58.3% (7/12) were free of remote metastases and warranted treatment with limited radiotherapy. True BFGs with remote metastases and all false BFGs should be treated with craniospinal irradiation. We provided evidence for the diagnosis of true BFGs that is useful for radiotherapy strategy, suggesting that the existence of metastasis to other locations is not a diagnostic criterion for a true BFG.

[Etiological diagnosis of central diabetes insipidus: about 41 cases]

The occurrence of polyuria-polydipsia syndrome with hypotonic urine requires careful diagnostic strategy. This study aims to evaluate diagnostic modalities for central diabetes insipidus. We conducted a retrospective study of 41 cases with central diabetes insipidus (CDI). Data were collected at the Department of Endocrinology, University Hospital La Rabta, Tunis, from 1990 to 2013. We identified the circumstances for detecting CDI, the abnormalities in anterior pituitary assessment and pituitary imaging. CDI occurred in the postoperative period in 20 patients. The average urine 24-hour volume was significantly higher in patients with CDI outside a surgical setting. Water deprivation test was successful in all patients who benefited from it. Outside of neurosurgery, infiltration causes were found in 6 patients and tumor causes were found in 6 patients. CDI was associated with empty sella turcica in 1 case and idiopathic sella turcica in 3 patients. Hypothalamic-pituitary magnetic resonance imaging and anterior pituitary balance sheet are systematic outside pituitary surgery setting and obvious primary polydipsia.

Pretreatment diagnosis of suprasellar papillary craniopharyngioma and germ cell tumors of adult patients

BACKGROUND AND PURPOSE

Suprasellar papillary craniopharyngiomas and germ cell tumors in adults share some clinical and imaging similarities but have different therapeutic strategies and outcomes. This study aimed to evaluate the pretreatment diagnosis of these 2 tumors to improve the therapeutic outcome.

MATERIALS AND METHODS

We retrospectively enrolled 18 adults with papillary craniopharyngiomas and 17 with germ cell tumors. The MR imaging findings were evaluated, including signal change and anatomic extension. The medical records were reviewed to collect clinical findings, management, and outcomes.

RESULTS

The clinical findings of papillary craniopharyngiomas versus germ cell tumors were as follows: age: 46 ± 13.9 years versus 23 ± 7.1 years (P < .0001); diabetes insipidus: 2/18 (11%) versus 11/17 (65%) (P = .001); recurrence 13/16 (81%) versus 4/17 (24%) (P = .0031). The MR imaging findings of papillary craniopharyngiomas versus germ cell tumors were as follows—pituitary stalk thickening: 1.6 ± 0.4 mm versus 5.4 ± 4.2 mm (P < .0001); vertical infundibular extension: 1/18 (6%) versus 16/17 (94%) (P < .0001); sagittal spheric shape: 17/18 (94%) versus 1/17 (6%) (P < .0001); diffusion restriction: 1/17 (6%) versus 8/12 (67%) (P = .0009).

CONCLUSIONS

Younger age, diabetes insipidus, MR imaging characteristics of restricted diffusion, and vertical infundibular extension favor the diagnosis of germ cell tumors. Spheric shape without infundibular infiltration provides clues to papillary craniopharyngiomas, which originate from the pars tuberalis and are located outside the third ventricle. We suggest that suprasellar germ cell tumor is possibly an intraventricular lesion. Appropriate treatment planning can be initiated according to the diagnosis and anatomic location.

Normal dimensions of the posterior pituitary bright spot on magnetic resonance imaging

Object

The normal pituitary bright spot seen on unenhanced T1-weighted MRI is thought to result from the T1-shortening effect of the vasopressin stored in the posterior pituitary. Individual variations in its size may be difficult to differentiate from pathological conditions resulting in either absence of the pituitary bright spot or in T1-hyperintense lesions of the sella. The objective of this paper was to define a range of normal dimensions of the pituitary bright spot and to illustrate some of the most commonly encountered pathologies that result in absence or enlargement of the pituitary bright spot.

Methods

The authors selected normal pituitary MRI studies from 106 patients with no pituitary abnormality. The size of each pituitary bright spot was measured in the longest axis and in the dimension perpendicular to this axis to describe the typical dimensions. The authors also present cases of patients with pituitary abnormalities to highlight the differences and potential overlap between normal and pathological pituitary imaging.

Results

All of the studies evaluated were found to have pituitary bright spots, and the mean dimensions were 4.8 mm in the long axis and 2.4 mm in the short axis. The dimension of the pituitary bright spot in the long axis decreased with patient age. The distribution of dimensions of the pituitary bright spot was normal, indicating that 99.7% of patients should have a pituitary bright spot measuring between 1.2 and 8.5 mm in its long axis and between 0.4 and 4.4 mm in its short axis, an interval corresponding to 3 standard deviations below and above the mean. In cases where the dimension of the pituitary bright spot is outside this range, pathological conditions should be considered.

Conclusions

The pituitary bright spot should always be demonstrated on T1-weighted MRI, and its dimensions should be within the identified normal range in most patients. Outside of this range, pathological conditions affecting the pituitary bright spot should be considered.

Predictors of neoplastic disease in children with isolated pituitary stalk thickening

BACKGROUND

The significance of pituitary stalk thickening (PST) on magnetic resonance imaging (MRI) is often unclear. We evaluated presenting symptoms, MRI findings, clinical course, and outcome predictors of patients with PST.

PROCEDURE

We used a computerized search of the medical record from 1995 to 2008 to identify patients with PST without pituitary mass on MRI. Baseline and follow-up MRIs were reviewed in a blinded fashion. Relevant clinical data were abstracted.

RESULTS

69 patients with reported PST and adequate imaging for review were identified; 42 met study criteria. Median age at first abnormal MRI was 13.6 years (range: 0.8-19.7); 43% were male. Median follow-up was 3.4 years (range 0-12.8). Patients with diabetes insipidus (DI) were significantly more likely to have a neoplastic process than those without (P = 0.0008). Of 16 patients with DI, 8 (50%) had a neoplastic process, including germ cell tumor (n = 4), Langerhans cell histiocytosis (n = 3), and lymphoma (n = 1). Among patients with DI, 7 (44%) also developed anterior pituitary hormone dysfunction (APD), either at presentation or on pre-biopsy follow-up, including 6/8 patients with stalk neoplasm and only 1/8 patients with non-neoplastic PST (P = 0.04). Twenty-six patients presented without DI; none was found to have neoplasm of the stalk except one patient with craniopharyngioma. Progression of PST on follow-up imaging was significantly associated with a subsequent neoplastic diagnosis (P = 0.04).

CONCLUSION

Patients with PST without DI are unlikely to have a neoplastic process. Among patients with DI, APD or progressive stalk increase over time are predictive of neoplasia.

Central diabetes insipidus as the inaugural manifestation of Langerhans cell histiocytosis: natural history and medical evaluation of 26 children and adolescents

CONTEXT

Isolated central diabetes insipidus (CDI) can be the first manifestation of Langerhans cell histiocytosis (LCH), creating diagnostic dilemmas such as dysgerminoma and other inflammatory lesions.

METHOD

In 2010, the French national LCH registry had enrolled 1236 LCH patients under 18 yr of age. Isolated CDI was the initial presentation of LCH in 26 patients. We reviewed their clinical and magnetic resonance imaging (MRI) features.

RESULTS

Median age at the diagnosis of CDI was 9.6 yr (1.8-16.3), and median follow-up after CDI diagnosis was 9.9 yr (3.5-26.6). In addition to CDI, two patients had visual field defects, four had secondary amenorrhea, and 11 had anterior pituitary deficiency. Cerebral imaging (including computed tomography in two cases), performed in 22 patients within 3 months of CDI diagnosis, showed pituitary stalk thickening in 14 patients, which was moderate (3.0-7 mm) in nine cases and marked (>7 mm) in five cases. In eight cases, the lesion extended to the floor of the third ventricle. One child with LCH presented with a mild enlarged sellar content. During follow-up, 22 patients developed extrapituitary involvement, mainly of bone (n = 15), lung (n = 9), and skin (n = 9). Pituitary biopsy was performed in eight cases and was conclusive in six cases.

CONCLUSIONS

Pituitary stalk thickening can be observed in LCH as well as lesions extending to the floor of the third ventricle. In all cases but one, the intrasellar content was not enlarged. Long-term follow-up with close attention to bone, skin, and lung disorders may lead to the diagnosis of LCH.

Lymphocytic infundibulo-neurohypophysitis and infundibulo-panhypophysitis regarded as lymphocytic hypophysitis variant

Lymphocytic infundibulo-neurohypophysitis (LINH) was first reported by Saito et al. and Imura et al. as a cause of idiopathic central diabetes insipidus. Magnetic resonance (MR) imaging with a contrast medium demonstrates thickening of the pituitary stalk, enlargement of the neurohypophysis, or both with homogeneous enhancement. Histological examination reveals a posterior pituitary that is heavily infiltrated by lymphocytes with occasional plasma cells and other inflammatory cells. In early reports of the disorder, the lesion seemed to be limited to the neurohypophysis, but the present review showed cases with a combination of hypopituitarism and diabetes insipidus. Some of them showed partial hypopituitarism. The so-called lymphocytic infundibulo-panhypophysitis (LIPH) is now regarded as a lymphocytic hypophysitis variant. LINH and LIPH are essentially self-limited. In typical cases, conservative care with steroids and hormone replacement is recommended. Surgical intervention should be avoided because the natural course of the disorder may be self-limited. Pathophysiology of the disorder is still unknown. The unique clinical manifestations of the disorder are discussed and reviewed here.

Granulomatous Pachymeningitis Around the Sella Turcica (Tolosa-Hunt Syndrome) Involving the Hypophysis-Case Report-

A 50-year-old female presented with right painful abducens nerve palsy persisting for 4 months and mild panhypopituitarism with diabetes insipidus for 6 months. T(1)-weighted magnetic resonance (MR) imaging of the sellar region showed a homogeneously enhanced mass lesion in the right cavernous sinus which seemed to extend from the swollen pituitary gland. T(2)-weighted MR imaging clearly showed the mass in the right cavernous sinus and the thickened dura mater of the sellar floor as hypointense, and the enlarged pituitary gland as isointense. Biopsy of the thickened dura mater and swollen pituitary gland was performed via the transsphenoidal approach. Histological examination revealed inflammation and collagen fiber formation in these regions. The diagnosis was secondary panhypophysitis resulting from granulomatous pachymeningitis involving the cavernous sinus (Tolosa-Hunt syndrome). Corticosteroid therapy was begun after the biopsy. Her periorbital pain and diplopia were relieved, but diabetes insipidus persisted. Follow-up MR imaging showed a decrease in the volumes of the pituitary gland and the mass in the cavernous sinus.

Neurohypophyseal granulomatous germinoma invading the right cavernous sinus: case report and review of the literature

We encountered a rare case of neurohypophyseal germinoma with a prominent granulomatous reaction, which invaded the right cavernous sinus. The neuroimaging and histopathology features in this case were unique, distinguishing it from other types of suprasellar lesions. A 13-year-old boy presented with loss of appetite and polyuria; both symptoms were present for 1 year, and headache, general fatigue and blurred vision present for the prior 2 months. On admission, neurological examination indicated bitemporal hemianopsia and optic atrophy. Endocrinological exam showed panhypopituitarism. Tumor markers such as alpha-fetoprotein, human growth hormone, carcinoembryonic antigen, and placental alkaline phosphatase were negative. Brain CT revealed a suprasellar tumor with calcification. MR T(1)-weighted and T(2)-weighted images showed the tumor to be isointense to normal brain parenchyma and to be enhanced densely. The tumor also involved the right cavernous sinus, so that a biopsy was performed by the transsphenoidal approach. On pathologic examination of the specimen, typical large tumor cells with lymphocytic cell infiltration and prominent granulomatous reaction were observed. Neurohypophyseal granulomatous germinoma was diagnosed. Radiotherapy was performed with a total dose of 51 Gy and the tumor shrank remarkably. The patient returned to school under hormone replacement therapy.

Parasellar tumors: suprasellar and cavernous sinuses

This article will review the presentation and imaging appearance of tumors affecting the area around the pituitary gland. For convenience, the lesions will be discussed in order of the regions they usually affect. For example, lesions affecting the suprasellar region include craniopharyngiomas, optic or hypothalamic gliomas, germ cell tumors, epidermoids, dermoids, hamartomas, lipomas, and choristomas. Tumors that commonly affect the parasellar cavernous sinus include schwannomas and meningiomas. Tumors like chordomas may arise in the sphenoid bone or clivus and affect the sella. Metastasis, meningiomas and aneurysms may involve any area around the sella. For a detailed discussion of normal anatomy and imaging protocols, see the first article of this monograph.

Central diabetes insipidus: Is it Langerhans cell histiocytosis of the pituitary stalk? A diagnostic pitfall

Central diabetes insipidus (CDI) is a rare disorder that may be caused by a variety of diseases. In pediatric and adolescent patients the most common causes for CDI are Langerhans cell histiocytosis (LCH) and germinoma. To avoid a potentially hazardous biopsy of the hypothalamic pituitary region it is recommended to evaluate patients with CDI carefully to identify potential extracranial lesions. Since LCH is the most common systemic disease that may cause CDI, special focus is paid to the identification of LCH lesions. We report on a 9(1/2) year old girl who presented with central diabetes insipidus and a thickening of the pituitary stalk on magnetic resonance imaging. Diagnostic workup revealed a history of recurrent ear infections and a compressed 6th thoracic vertebral body on radiographs. Based on these findings LCH was anticipated. Upon growth of the pituitary stalk lesion the patient was treated with LCH standard chemotherapy. After an initial shrinkage of the lesion, a further growth of the pituitary stalk lesion was observed and the tumor was resected. Histopathology revealed germinoma. This case underscores the importance of a istopathologically proven diagnosis in patients with HPR tumors before the initiation of a specific therapy, even if the clinical findings are highly suggestive.

Clinical management of primary central nervous system germ cell tumors

Despite excellent long-term results for patients with germinoma treated with radiation therapy, the potential for late effects makes the treatment controversial. On the other hand, most patients with non-germinomatous tumors treated by conventional treatment with surgery and radiation therapy fail to survive longer than 3 years. After combination chemotherapy with cisplatin was confirmed to be effective in gonadal germ cell tumors, germ cell tumors of the brain became candidates for chemotherapy. The author reviews several prospective phase II studies that are being investigated to assess the effect of combination chemotherapy and radiation therapy for germ cell tumors. The aim of these studies is to reduce the volume and dose of radiation therapy for germinoma and prolong the survival of patients of non-germinomatous tumors. For germinoma, a trial with chemotherapy alone failed, with a high rate of recurrence, but Japanese and European trials with reduced-dose chemotherapy and a smaller volume of radiation therapy have resulted in high event-free survival (EFS) rates. Ongoing phase II studies with combined chemotherapy and radiation therapy for non-germinomatous tumors will result in a 5-year survival rate of greater than 50%, which is better than that achieved by radiation therapy alone.

MRI and CT findings of neurohypophyseal germinoma

OBJECTIVE

Magnetic resonance (MR) imaging and computed tomography (CT) findings of neurohypophyseal germinoma have not previously been described in detail. The purpose of the present study was to establish the spectrum of MR imaging and CT findings in neurohypophyseal germinomas.

MATERIALS AND METHODS

MR and CT images of 13 consecutive patients (seven males, six females; mean age: 15 years; range: 6-31 years) with neurohypophyseal germinoma were retrospectively analyzed. The diagnosis had been made either histologically (n=8) or clinically according to established criteria (n=5). All patients had been examined using MR imaging and CT before treatment.

RESULTS

On MR imaging, infundibular thickening (up to 16 mm) was observed in all 13 cases. Hyperintensity of the posterior pituitary on T1-weighted image was absent in all 13 cases (100%) and 12 of the 13 displayed central diabetes insipidus. Ten germinomas (77%) were isointense to cerebral cortex on T1-weighted image, but variable intensities were exhibited on T2-weighted image. MR images revealed intratumoral cysts in six cases (46%), most of which demonstrated intra-third ventricular extension. Eleven of the 13 cases (85%) revealed hyperdense solid components on unenhanced CT. Calcification was absent in all cases (100%).

CONCLUSION

Infundibular thickening, absence of the posterior pituitary high signal on T1-weighted image, lack of calcification and hyperdensity on unenhanced CT are common imaging features of neurohypophyseal germinoma.

Late recurrence of pineal germinoma

BACKGROUND

Cerebral germinomas and their occasional recurrences can usually be cured by irradiation, chemotherapy, or a combination of the two treatment modalities. Late recurrences, as in our case, are distinctly rare.

CASE DESCRIPTION

This patient presented at age 24 with a calcified tumor in the pineal area. The radiological diagnosis was germinoma. No tissue diagnosis was obtained. Radiation therapy was given, and there was a complete response. The patient's symptoms reappeared 13 years later. Imaging studies revealed a lesion in the anterior corpus callosum. A germinoma was diagnosed by stereotactic biopsy. Because of complications attributed to the initial course of radiation therapy, no further radiation was given. Five courses of chemotherapy resulted in a partial remission lasting six months. The patient later died because of massive tumor progression with intracerebral, intraventricular, cerebellar, and meningeal dissemination.

CONCLUSIONS

As this case illustrates, exceptional recurrences of cerebral germinomas may appear even many years after adequate initial treatment with radiation and chemotherapy.

Neurohypophyseal germinoma traced from its earliest stage via magnetic resonance imaging: case report

BACKGROUND

We report a case in which magnetic resonance imaging (MRI) documented the formation of a neurohypophyseal germinoma from its earliest stage.

CASE DESCRIPTION

A 9-year-old girl presented with polyuria, polydipsia, and growth retardation. Urinary and endocrinological examination indicated diabetes insipidus (DI) and growth hormone deficiency. No clear evidence of a mass in the hypothalamo-pituitary area was apparent on the first MRI scan. Follow-up MRIs and endocrinological examinations revealed that a tumor, arising from the stalk and posterior lobe of the pituitary gland, formed a mass and caused anterior pituitary function to deteriorate. Histologic diagnosis was germinoma based on open biopsy.

CONCLUSION

Radiologic findings in this case indicated the primary site of this intrasellar germinoma to be the hypothalamo-neurohypophyseal region, designating this a "neurohypophyseal germinoma."

Central diabetes insipidus in children and young adults

BACKGROUND

Central diabetes insipidus is rare in children and young adults, and up to 50 percent of cases are idiopathic. The clinical presentation and the long-term course of this disorder are largely undefined.

METHODS

We studied all 79 patients with central diabetes insipidus who were seen at four pediatric endocrinology units between 1970 and 1996. There were 37 male and 42 female patients whose median age at diagnosis was 7.0 years (range, 0.1 to 24.8). All patients underwent magnetic resonance imaging (MRI) and periodic studies of anterior pituitary function. The median duration of follow-up was 7.6 years (range, 1.6 to 26.2).

RESULTS

The causes of the central diabetes insipidus were Langerhans-cell histiocytosis in 12 patients, an intracranial tumor in 18 patients, a skull fracture in 2 patients, and autoimmune polyendocrinopathy in 1 patient; 5 patients had familial disease. The cause was considered to be idiopathic in 41 patients (52 percent). In 74 patients (94 percent) the posterior pituitary was not hyperintense on the first MRI scan obtained, and 29 patients (37 percent) had thickening of the pituitary stalk. Eighteen patients had changes in the thickness of the pituitary stalk over time, ranging from normalization (six patients) or a decrease in thickness (one patient) to further thickening (seven patients) or thickening of a previously normal stalk (four patients). Anterior pituitary hormone deficiencies, primarily growth hormone deficiency, were documented in 48 patients (61 percent) a median of 0.6 year (range, 0.1 to 18.0) after the onset of central diabetes insipidus.

CONCLUSIONS

Most children and young adults with acquired central diabetes insipidus have abnormal findings on MRI scans of the head, which may change over time, and at least half have anterior pituitary hormone deficiencies during follow-up.

Langerhans cell histiocytosis limited to the pituitary-hypothalamic axis--two case reports

Langerhans cell histiocytosis rarely presents as a solitary lesion in the pituitary-hypothalamic region, and is indistinguishable from germinoma, which occurs much more frequently, especially in Japanese. A 14-year-old girl and a 9-year-old girl presented with polydipsia and polyuria as the initial symptoms. Magnetic resonance (MR) imaging demonstrated a round mass at the pituitary stalk appearing as isointense on T1-weighted imaging and hyperintense on T2-weighted imaging. Endocrinological examination revealed mild hypopituitarism with central diabetes insipidus. Both patients underwent open craniotomy. Histological examination revealed granulomatous tissue with eosinophil infiltration and frequent Langerhans histiocyte clustering, compatible with the diagnosis of Langerhans cell histiocytosis. Low-dose local irradiation of 20 Gy was administered. First patient was followed up for 8 years, and her hypopituitarism gradually improved to a minimal level with only amenorrhea as the residual symptom. Recent MR imaging showed no residual mass at the region. Second patient was followed up for 15 months, and her diabetes insipidus is stable. MR imaging performed 5 months after the treatment showed marked reduction of the mass. These cases reemphasize the importance of histological diagnosis for lesions with similar neuroimaging appearances. Biopsy and low-dose irradiation are an effective treatment for this rare and essentially benign lesion, as opposed to attempting total removal of the mass.

Encephalomyelitis, brain tumors, neuromuscular diseases and miscellaneous disorders

Japanese neuropathologists have accomplished and contributed to a considerable number of achievements, and some of these are cited in other articles in this issue. Several of these achievements as well as other miscellaneous discoveries are briefly summarized in the present paper. Specifically these relate to rabies postvaccinal encephalomyelitis, experimental allergic encephalomyelitis, brain tumor research, neuromuscular disorders, schizophrenia, viral infections, glial inclusion body in multiple system atrophy, and the neurobiology of glia.

Immature teratoma originating from the pituitary gland: case report

OBJECTIVE AND IMPORTANCE

Recently, it has been suggested that the primary site of suprasellar germinomas is the neurohypophysis, but nongerminomatous germ cell tumors originating from the pituitary gland have been rarely reported.

CLINICAL PRESENTATION

A 27-year-old man presented with panhypopituitarism, bitemporal hemianopsia, and mild right oculomotor nerve paralysis. Diabetes insipidus was not observed. The tumor was shown by magnetic resonance imaging to extend and invade bilateral cavernous sinuses, sellar and clival dura mater, and the sphenoid sinus mucosa.

INTERVENTION

Transsphenoidal removal yielded a diagnosis of immature teratoma. Serum alpha-fetoprotein was prominently elevated. Magnetic resonance imaging and surgical findings of the superiorly displaced residual pituitary gland strongly suggest the pituitary origin of this rare tumor.

CONCLUSION

In contrast to the neurohypophyseal germinomas, nongerminomatous malignant germ cell tumors originating from the pituitary gland tend not to be associated with diabetes insipidus and thus mimic adenomas. Evaluation of the tumor markers is necessary in young patients with cavernous sinus syndrome and invasive pituitary tumors with heterogeneous intensity revealed by magnetic resonance imaging.

Suprasellar germinomas in childhood and adolescence: diagnostic pitfalls

The clinical and neuro-endocrine data of seven young male patients with suprasellar germinomas seen between 1984 and 1992 are reported. The most common initial symptom was 'idiopathic' central diabetes insipidus (DI), which occurred in all seven patients. The time interval between the appearance of this first clinical sign and the definitive diagnosis of a suprasellar germinoma ranged from 3 to 66 months. Raised prolactin levels and growth hormone deficiency were indicators of a process located in the hypothalamic-pituitary region. An increased beta-HCG level in the serum or the CSF confirmed the diagnostic suspicion of a germinoma and was helpful as a tumor marker in follow-up. Neuro-radiologic studies (CT or MRI) were also disappointing in the early stage when patients presented only with DI. Later on, as patients developed additional symptoms or signs related to the tumor, imaging studies were positive. Given the variable rate of tumor progression, the nonspecific early signs of hypothalamic-pituitary dysfunction (DI) as well as the often negative early imaging studies, the diagnosis of suprasellar germinoma is difficult but should always be considered in the presence of so-called 'idiopathic' central DI. Repeated brain MRIs are mandatory in young patients with idiopathic DI in order not to miss an underlying suprasellar germinoma.

Occult neurohypophyseal germinomas in patients presenting with central diabetes insipidus

Although neurohypophyseal germinoma is known be a common initial symptom in cases of diabetes insipidus (DI), its radiological detection may take months or years even by a high-resolution magnetic resonance (MR) imaging. The term “occult neurohypophyseal germinoma” denotes such cases, but its clinical picture remains obscure.

Of seven patients with neurohypophyseal germinoma presenting with DI during the last 5 years, three patients showed no evidence of tumor at the onset of DI and were treated as “idiopathic” DI. Neurohypophyseal germinoma was eventually diagnosed in these three patients as the tumor became evident on sequential MR imaging studies and the patients were successfully treated with chemotherapy and radiation therapy. To delineate the clinical features of the occult neurohypophyseal germinoma, the authors analyzed endocrinological aspects and MR images in these patients and compared them with those in two patients with true idiopathic DI and four patients with overt neurohypophyseal germinoma and DI. Nine previously reported cases in the literature were reviewed. During the stage at which the germinoma gave no notable change on MR images, patients often displayed anterior pituitary dysfunction, particularly growth hormone (GH) deficiency, or an elevation of serum or cerebrospinal fluid human chorionic gonadotropin-beta. Preceding the appearance of an obvious tumor mass, a slight swelling of the pituitary stalk with loss of normal hyperintensity of the posterior pituitary lobe was a common finding on MR imaging.

Central DI associated either with an enlarged stalk, decreased GH secretion, or an elevated serum human chorionic gonadotropin-beta should prompt the diagnosis of an occult germinoma.

Metachronous neurohypophyseal germinoma occurring 8 years after total resection of pineal mature teratoma

BACKGROUND

Metachronous germ cell tumor in the central nervous system is extremely rare. To our knowledge, only one patient presenting conceivable metachronous intracranial germ cell tumor has been reported.

CASE REPORT

A neurohypophyseal germinoma occurring 8 years after total resection of a pineal mature teratoma is presented. The patient underwent total resection of a large pineal mass in 1987. Histologic investigation revealed a mature teratoma without any immature or germinomatous components. In 1995, he developed diabetes insipidus. Magnetic resonance imaging depicted an intrasellar mass extending to the floor of the third ventricle. A transsphenoidal biopsy revealed histologically pure germinoma.

CONCLUSION

The second neurohypophyseal germinoma was considered to be a de novo metachronous neoplasm rather than a recurrence of the original mature teratoma.

Primary intracranial germ cell tumors: a clinical analysis of 153 histologically verified cases

The authors analyzed 153 cases of histologically verified intracranial germ cell tumors. The histological diagnosis was germinoma in 63 patients (41.2%), teratoma in 30 (19.6%), and other types of tumors in 60 patients (39.2%). The patients were treated by a consistent policy of surgical removal with histological verification followed by radiation therapy with or without chemotherapy. The 10- and 20-year survival rates of patients with pure germinoma were 92.7% and 80.6%, respectively. The 10-year survival rates of patients with mature teratoma and malignant teratoma were 92.9% and 70.7%, respectively. Patients with pure malignant germ cell tumors (embryonal carcinoma, yolk sac tumor, or choriocarcinoma) had a 3-year survival rate of 27.3%. The mixed tumors were divided into three subgroups: 1) mixed germinoma and teratoma; 2) mixed tumors whose predominant characteristics were germinoma or teratoma combined with some elements of pure malignant tumors; and 3) mixed tumors with predominantly pure malignant elements. The 3-year survival rates were 94.1% for the first group, 70% for the second group, and 9.3% for the third group, and the differences were statistically significant. Twenty-six patients with malignant tumors received chemotherapy that consisted of cisplatin and carboplatin combinations with or without radiation therapy. However, chemotherapy was not significantly more effective than radiation therapy alone. From these treatment results, the authors classified tumors into three groups with different prognoses and proposed a treatment guideline appropriate for the subgroups.

MRI of intracranial germ cell tumours

We reviewed MRI findings in proven intracranial germ cell tumours in 22 cases, 12 of whom received Gd-DTPA. On T1-weighted images, the signal intensity of the tumour parenchyma was moderately low in 19 cases and isointense in 3; on T2-weighted images, it was high in all cases. Regions of different intensity thought to be cysts were found in 17 (77%): 7 of 12 patients with germinoma (58%) and in all other cases. Of the 13 patients with pineal lesions T1-weighted sagittal images showed the aqueduct to be obstructed in 5, stenotic in 7 and normal in 1. Strong contrast enhancement was observed in all 12 cases. Of the 14 patients with suprasellar lesions, 5 were found to have an intrasellar extension, and in 3 of these, the normal pituitary gland, which could be distinguished from the tumour, was displaced anteriorly. Ten patients (45%) had multiple lesions.

CT and MRI features of intracranial germ cell tumors

The computed tomographic (CT) and magnetic resonance imaging (MRI) features of 73 histologically proven primary intracranial germ cell tumors were analysed. CT images were available for all 73 patients, and 22 of them were also examined by MRI. The tumors were classified as germinoma, mature teratoma, immature or malignant teratoma, yolk sac tumor, choriocarcinoma, embryonal carcinoma and mixed type. Germinoma was revealed as a high- or slightly high-density area on plain CT scan, and was enhanced homogeneously. MRI revealed iso- or slightly low signal intensity on T1-weighted images, and iso- or high intensity on T2-weighted images. Mature teratoma, which had a clear margin on neuroradiological images, was characterized by mixed density on CT scans, often showing large cysts and area of calcification. Immature or malignant teratoma had a similar pattern to that of mature teratoma, but the cystic components and area of calcification tended to be less and smaller respectively. The tumor margin was obscure in malignant teratoma, and perifocal edema was observed in some cases. The shape of yolk sac tumors was irregular. Plain CT scan revealed an iso- or low-density mass with good heterogeneous enhancement. Perifocal edema was observed in some cases. In mixed germ cell tumors, MRI imaging was useful for detecting teratomatous components, particularly fatty components. Although definite histological diagnosis cannot be achieved by CT and/or MRI alone, detailed analysis of neuroradiological images are useful for predicting the histological diagnosis.

Successful treatment of recurrent malignant germ cell tumors: report of two cases

We report two patients with recurrent malignant germ cell tumors who were successfully treated with radiation therapy and cisplatin combination chemotherapy. Patient 1, who had a suprasellar mixed yolk sac tumor, had been free of tumor for 3.5 years after cisplatin/vinblastine/bleomycin combination chemotherapy alone but showed a recurrent tumor in the pineal region. In Patient 2, who had a pineal alpha-fetoprotein-producing tumor, recurrent tumors appeared in the lateral ventricle 3 years after the tumor was controlled by radiation and cisplatin/vinblastine/bleomycin therapy. They were treated successfully again by radiation therapy, followed by cisplatin and etoposide combination therapy, and they have been free of tumor for 5.5 and 7 years after recurrence, respectively. The total dose of cisplatin in both patients exceeded 1,000 mg/m2, which would have contributed to the control of the recurrent tumors. Anterior pituitary dysfunction observed in Patient 1 did not improve, even after tumor disappearance by chemotherapy, suggesting severe damage to the neurohypophysis by direct invasion of the tumor.

Germ cell tumor in the hypothalamo-neurohypophysial region: clinical features and treatment

Twenty-one patients with germ cell tumors (17 germinomas and 4 teratomas) involving the hypothalamic-neurohypophysial (HN) region were reviewed retrospectively. Eleven patients were males and 10 females, and their ages ranged from 7 to 45 years (average 18.5 years). Diabetes insipidus was the initial and the most prominent symptom in most germinomas; in teratomas the most prominent symptom was visual disturbance. Fifteen patients with germinomas were treated by radiotherapy, and 4 with teratomas were treated by surgical resection alone. Two recent germinoma patients with extensive CSF dissemination were treated with systemic chemotherapy consisting of anticancer platinum drugs and etoposide, which resulted in a complete disappearance of the tumors. Patients with germinoma treated after the introduction of CT scanning had a greatly improved mortality rate, and their actual survival rate was 87.5% over 10 years. On the basis of this review, the authors consider that diagnosis at an early stage of the disease and chemotherapy, which can be an effective therapeutic alternative to radiation therapy, may improve not only the mortality rate but also the quality of life of patients with HN germ cell tumors.