Colloid cyst of the third ventricle. A comparative immunohistochemical study of neuraxis cysts and choroid plexus epithelium

Endoscopic trans-septal interforniceal approach for excision of colloid cysts of the third ventricle using the rotational technique

Colloid cysts of the third ventricle are benign intracranial lesions that account for 0.5 to 2% of all brain tumors and are even rarer in pediatric population. Dandy was the first to successfully excise a colloid cyst of the third ventricle via a transcortical transventricular approach in 1921. For several decades to follow, the transcortical transventricular and transcallosal microsurgical approaches remained the cornerstone of surgical management of these lesions. With time and refinements in endoscopic equipment and techniques, endoscopic resection of colloid cysts evolved into a currently well-established and appealing minimally invasive alternative to microsurgery. Endoscopic endochannel techniques for colloid cysts of the third ventricle may either be transforaminal or trans-septal interforniceal, depending on the pathoanatomical features of the colloid cyst and its relation to the juxtaposed anatomical structures. The endoscopic trans-septal interforniceal approach is required to access the rare subset of colloid cysts that extend superior to the roof of the third ventricle between the two fornices insinuating themselves between the leaflets of the septum pellucidum. In this article, the surgical technique of the endochannel endoscopic trans-septal interforniceal approach is elaborated upon. A representative case is presented along with an operative video.

Sellar colloid cyst: Peculiar radiological characteristics of a common lesion at an uncommon location

Background

Colloid cysts, common benign lesions of the third ventricle, have rarely been reported in uncommon extraventricular locations such as the pituitary fossa. Even in the sellar region, it is usually seen between the anterior and posterior pituitary lobes (pars intermedia).

Case Description

Here, we report a case of a female patient, who was incidentally diagnosed with a sellar colloid cyst, while being evaluated for nonspecific holocranial headache. On imaging, there was a lesion located in the anterior sellar region, compressing the whole pituitary gland posteriorly (first reported case to the best of our knowledge), that was found to be a colloid cyst intraoperatively during microsurgical excision through transnasal transsphenoidal route.

Conclusion

This rare entity should be kept in mind while considering lesions of the pituitary region, as evident by typical radiological features, in spite of being located in a less likely site.

Distribution of Monocarboxylate Transporters in Brain and Choroid Plexus Epithelium

The choroid plexus (CP) plays central roles in regulating the microenvironment of the central nervous system by secreting the majority of cerebrospinal fluid (CSF) and controlling its composition. A monolayer of epithelial cells of CP plays a significant role in forming the blood-CSF barrier to restrict the movement of substances between the blood and ventricles. CP epithelial cells are equipped with transporters for glucose and lactate that are used as energy sources. There are many review papers on glucose transporters in CP epithelial cells. On the other hand, distribution of monocarboxylate transporters (MCTs) in CP epithelial cells has received less attention compared with glucose transporters. Some MCTs are known to transport lactate, pyruvate, and ketone bodies, whereas others transport thyroid hormones. Since CP epithelial cells have significant carrier functions as well as the barrier function, a decline in the expression and function of these transporters leads to a poor supply of thyroid hormones as well as lactate and can contribute to the process of age-associated brain impairment and pathophysiology of neurodegenerative diseases. In this review paper, recent findings regarding the distribution and significance of MCTs in the brain, especially in CP epithelial cells, are summarized.

Nonneoplastic and noninfective cysts of the central nervous system: A histopathological study

Nonneoplastic epithelial cysts involving the central nervous system are diverse and are predominantly developmental in origin. This study represents a surgical series describing the histopathological features of 507 such epithelial cysts with clinical and imaging correlation. Age at surgery ranged from 7 months to 72 years (mean: 33 years) affecting 246 male and 261 female patients. Colloid cyst was the most frequently resected cyst, followed by epidermoid cyst, arachnoid cyst, Rathke cleft cyst, dermoid cyst, neurenteric cyst, Tarlov cyst, and choroid plexus cyst. Diagnosis was based on the location of the cysts and the nature of the lining epithelium. Rathke cleft cyst showed the highest propensity for squamous metaplasia, significant inflammation, and xanthogranulomatous reaction. Ulceration of lining epithelium and calcification were most frequent in dermoid cyst. Radiopathological concordance was maximal for colloid cyst, followed by epidermoid and arachnoid cysts. Epidermoid and dermoid cysts exhibited the highest propensity for local tumor progression, followed by Rathke cleft cyst.

Metabolites and Biomarker Compounds of Neurodegenerative Diseases in Cerebrospinal Fluid

Despite recent advances in diagnostic procedures for neurological disorders, it is still difficult to definitively diagnose some neurodegenerative diseases without neuropathological examination of autopsied brain tissue. As pathological processes in the brain are frequently reflected in the components of cerebrospinal fluid (CSF), CSF samples are sometimes useful for diagnosis. After CSF is secreted from the choroid plexus epithelial cells in the ventricles, some flows in the brain, some is mixed with intracerebral interstitial fluid, and some is excreted through two major drainage pathways, i.e., the intravascular periarterial drainage pathway and the glymphatic system. Accordingly, substances produced by metabolic and pathological processes in the brain may be detectable in CSF. Many papers have reported changes in the concentration of substances in the CSF of patients with metabolic and neurological disorders, some of which can be useful biomarkers of the disorders. In this paper, we show the significance of glucose- and neurotransmitter-related CSF metabolites, considering their transporters in the choroid plexus; summarize the reported candidates of CSF biomarkers for neurodegenerative diseases, including amyloid-β, tau, α-synuclein, microRNAs, and mitochondrial DNA; and evaluate their potential as efficient diagnostic tools.

Epidemiology and Clinicopathologic Study of Nonneoplastic Cystic Lesions of the Central Nervous System at a Tertiary Care Center

Background Nonneoplastic cysts of brain are a diverse group of benign lesions with variable etiopathogenesis. Due to different site and histogenesis, these lesions have wide clinicopathologic spectrum.

Objective The study was performed to evaluate epidemiology and clinicopathologic spectrum of nonneoplastic central nervous system (CNS) cysts highlighting the role of histopathology in the diagnosis as well as to compare the data with other institution’s data available in literature.

Materials and Methods All nonneoplastic CNS cysts reported from January 2013 to June 2020 in the Department of Pathology of Sawai Man Singh Medical College, Jaipur, were retrieved and reviewed. The data were evaluated for age, site, cyst wall lining, nature of cyst contents, and location (intracranial and spinal), using SPSS software version 20.0.

Results A total of 255 cases were reviewed with an incidence of 4.96% and an age range of 2 to 74 years with slight male preponderance. Among them there were 157, 34, 26, 24, and 2 cases of epidermoid, arachnoid, dermoid, colloid, and glioependymal cysts, respectively, and 1 case of perineural cyst. Infective cysts were much less common than noninfective cysts, accounting for two cases of neurocysticercosis and hydatid cysts each. All cyst types mainly presented with signs and symptoms of a mass lesion.

Conclusion Nonneoplastic cyst mainly presented like a CNS mass lesion with overlapping clinical features, and image finding revealing the key role of histopathological analysis. Epidermoids were the most common type of these cysts in the present series followed by the arachnoid cysts.

Immunohistochemical expression of osteopontin and collagens in choroid plexus of human brains

Evidence showing the functional significance of the choroid plexus is accumulating. Although it is clinically well‐known that calcification is frequently seen in the choroid plexus of aged human brains, it is unclear why calcification occurs in the aged choroid plexus and what exert effects on the calcification has. In this study, immunohistochemical localizations of collagens and other molecules related to fibrosis or calcification were investigated on the choroid plexus of autopsied human brains. Densely fibrous or calcified materials were located in the stroma just below the epithelial cells of the choroid plexus of all human brains examined. Immunoreactivity for collagen type I was identified in the stroma just below the epithelial cells, consistent with the densely fibrous or calcified area, whereas that for collagen type III was observed in almost all stroma other than the densely fibrous or calcified areas. Linear or membranous immunoreactivity for collagen type IV was intermittently localized on the epithelium‐facing side of the materials, suggesting an injured basement membrane. In addition, clear immunoreactivity for osteopontin was localized on the epithelium‐facing side of the fibrous or calcified materials as well as in the cytoplasm of epithelial cells. These findings indicate that collagen type I exists in contact with osteopontin in and around the densely fibrous or calcified materials in the choroid plexus. They suggest that the densely fibrous or calcified materials are deposited in the subepithelial stroma just below an injured basement membrane of epithelial cells via the collagen type I and osteopontin.

Nonneoplastic Cystic Lesions of the Central Nervous System-Histomorphological Spectrum: A Study of 538 Cases

Background A wide spectrum of non-neoplastic cystic lesions can occur in the central nervous system (CNS). These are uncommon, benign and of diverse aetiology, pathogenesis and clinical presentation.The spectrum of these lesion varies based on the location and in turn histogenesis. Objectives To evaluate the pathologic spectrum of non-neoplastic cystic lesions in the CNS (both developmental and acquired) and highlight the role of histopathology in the diagnosis of these cystic lesions. Settings and Design This was a retrospective study done at Department of Neuropathology,NIMHANS. Materials and Methods All the histologically diagnosed non-neoplastic cystic lesions of CNS submitted to the Department of Neuropathology between 2014 and 2017 were reviewed in this study. The data was analysed in relation to the type of cysts, location(intracranial and spinal), and clinical profile using SPSS software version 17.0. Results The study included 538 cases with patient age ranging from 5 months to 90 years [M:F:1:1.05]. Non-infective cysts (489/538, 90.8%) predominated over the infective cysts (49/539, 9.2%) with epidermoid cysts (132/538, 24.5%) being the most frequent one followed by colloid cysts (126/538, 23.4%) and arachnoid cysts (111/538,20.6%). The most common infective cyst was neurocysticercosis (42/538, 7.8%) followed by hydatid cyst (7/538, 1.3%). Intracranial cysts (415/538, 77.1%) were more common than spinal ones (123/538, 22.9%). Conclusions: A variety of cystic lesions occur in the CNS with overlapping clinical features, image findings and lining. Hence, histological analysis plays a crucial role in the evaluation of these lesions.

Magnetic resonance characterization of the 'dot sign' in colloid cysts of the third ventricle

PURPOSE

To determine the incidence of the 'dot sign' in patients with colloid cysts of the third ventricle and to characterise its MRI appearances.

MATERIALS AND METHODS

Single institution retrospective analysis between January 2007 and October 2016 of all patients with either an imaging or imaging and histology-confirmed diagnosis of colloid cysts of the 3rd ventricle was undertaken. For all cases, MRI signal intensities of the cyst fluid component were graded by two independent radiologists relative to brain parenchyma. Presence of a dot, and if present, its size and relative position within the cyst were recorded. Signal intensities of the dot were then similarly assessed.

RESULTS

37 cases of colloid cyst were identified. Of these 37.8% (n = 14) demonstrated the dot sign. The majority (11 of 14) were observed inferiorly within the cyst; two cases were anteroinferior, and one other was posterior. All identified intracystic nodules displayed low signal intensity with respect to cyst fluid on T2 weighted sequences, and only two nodules were hypointense to fluid on T1-weighted imaging, with the remainder either iso- or hyperintense.

CONCLUSIONS

An intracystic low T2 'dot' is a common MRI feature of colloid cysts of the third ventricle, and to our knowledge not previously systematically described. Presence of such a dot should not only not dissuade from a diagnosis of colloid cyst being made, but should in fact be used to strengthen the imaging diagnosis.

Endodermal Cyst of the Third Nerve in a Child

Endodermal cysts, also known as neurogenic, neuroenteric, foregut, bronchogenic, respiratory, epithelial, teratomatous, or gastrocytoma cysts, can be found in the central nervous system, predominantly in the subarachnoid space of the cervical and thoracic spinal cord. We describe a child with an endodermal cyst of the third nerve and highlight neuroimaging findings, pathological correlation, clinical course, and patient management.

A choroid plexus cyst in the fourth ventricle of a Sprague-Dawley rat

Choroid plexus cysts are rare lesions in the brain and are reported in humans and dogs. Herein, we report a choroid plexus cyst found in a 10-week-old female Sprague-Dawley rat. Histologically, a cyst measuring approximately 600 μm in diameter was found in the fourth ventricle of the brain. The cyst was lined with a single layer of flattened cells and was present in the connective tissue of the choroid plexus. Next to the cyst, a dilated tube was found with a similar morphology to the epithelium of the choroid plexus. Immunohistochemistry revealed that flattened cells lining the cyst were positive for cytokeratin and vimentin, and negative for GFAP and S-100, which is the same as in the normal choroid plexus, excluding vimentin. We diagnosed the present cyst as a spontaneously occurring choroid plexus cyst that was considered to be undergoing the epithelial-mesenchymal transition.

Choroid Plexus Cyst in a Neonatal Burmeister's Porpoise (Phocoena spinipinnis)

Neuroectodermal developmental anomalies are reported rarely in cetaceans and central nervous system cysts are not described. We describe the gross, microscopical, histochemical and immunohistochemical features of a neuraxial myelencephalic cyst in a stranded neonatal Burmeister's porpoise (Phocoena spinipinnis). Grossly, a subdural, extra-axial, well-demarcated, yellow fluid-filled cystic structure (1.9 × 1.6 × 1 cm) expanded the left foramen of Luschka, the left caudolateral cerebellar recess and the left cranioventral myelencephalon. The cyst displaced the ipsilateral ventral paraflocculus and distended the underlying cranial nerves IX, X, XI and XII. Microscopically, the cystic structure was lined by a monolayer of low cuboidal to flattened epithelium supported by a thin fibrovascular matrix. Immunohistochemistry (IHC) revealed strong and diffuse expression of AE1/AE3 and focal positivity for vimentin. IHC for epithelial membrane antigen, glial fibrillary acid protein, synaptophysin and S100 was negative. Based on these findings, an extra-axial cyst of the choroid plexus of the fourth ventricle (CCPFV) was diagnosed. The pathological relevance of the CCPFV in this case is uncertain. The cause of death involved severe perinatal interspecific (shark) trauma. The present case provides the first evidence of a neuroepithelial cyst in cetacean species.

Xanthogranulomatous colloid cyst of the third ventricle: Alter your surgical strategy

Colloid cysts are the most common benign neoplasms of the anterior third ventricle, mostly located at the level of the foramen of Monro and can often manifest as sudden onset headache or loss of consciousness. These cysts often have a well-defined cyst wall, mucinous or watery intracystic fluid and have a fairly good plane with the surrounding parenchyma. Occasionally, intracystic haemorrhage can lead to xanthogranulomatous inflammatory changes within the cyst resulting in focal thickening of the cyst wall and adhesion to the surrounding structures. Here we describe a case of xanthogranulomatous colloid cyst which is a very rare variant of colloid cyst.

Microsurgical Treatment of Colloid Cysts of the Third Ventricle

BACKGROUND

This study analyzes the results of surgical treatment in 377 patients with colloid cysts (CCs) of the third ventricle who were treated at the Burdenko Neurosurgery Institute from 1981 to 2015. Operations were performed by a single surgeon (the first author of the article).

METHODS

The transcallosal approach was used to remove CCs in 97% of cases. Total cyst removal was performed in 96% of cases (in 4% of cases, a small cyst capsule fragment was left on the veins and fornix); in 3 cases, the cyst recurred, which required its repeated removal.

RESULTS

Hydrocephalus symptoms regressed in 98% of patients. The most frequent complications in the early postoperative period were memory impairments of varying severity, with a tendency to regress by the time of discharge. Two patients had an intraventricular hematoma, which required operative exploration in 1 patient. There were 4 cases of meningitis (including 1 shunt-associated meningitis) and 5 cases of transient pyramidal insufficiency.

CONCLUSIONS

We made a preliminary assessment of the reasonability of the infratentorial supracerebellar approach for removal of CCs in 10 cases.

TWO UNCOMMON CASES OF COLLOID CYST OF THE THIRD VENTRICLE

Colloid cysts of the third ventricle of brain comprise 1-2% of all intracranial tumonrs [1]. They are increasingly being discovered incidentally, often in patients complaining of headache [2]. We came across two such cases in a large tertiary care service hospital in the past 20 years. Second case also had associated visual disturbances and seizures. Both met with fatal outcome. Autopsy revealed presence of colloid cyst in the third ventricle in both cases. It is proposed that to avoid fatal outcome in a patient reporting with frequent attacks of headache, the presence of colloid cyst in the third ventricle should be considered in differential diagnosis. In such cases, CT scan or MRI study of brain becomes an essential diagnostic tool.

Pituitary Colloid Cyst

Colloid cysts appear most commonly in the third ventricle, their occurrence in the sellar region is uncommon. The authors report a female patient with a pituitary colloid cyst. She was diagnosed incidentally with a sellar lesion by a routine paranasal computed tomography examination performed for planning of a dental implant surgery. Radiologic examinations revealed a pituitary lesion that was removed by transnasal transsphenoidal route. Her pathologic examination revealed that the lesion was a colloid cyst. Although rare, colloid cysts should be considered in the differential diagnosis of pituitary lesions

MRI features have a role in pre-surgical planning of colloid cyst removal

BACKGROUND

Endoscopic resection is becoming a well-established treatment option for patients with colloid cysts of the third ventricle. A disadvantage of this approach is the decreased ability to resect cysts in their entirety. Correlations between magnetic resonance imaging (MRI) features and cyst content could potentially help surgeons decide on the extent of resection and approach. We attempted to identify a correlation between patients' MRI imaging patterns and difficult cyst removal, post-operative adverse outcomes and the need for cerebrospinal fluid (CSF) diversion, in order to detect markers that may affect pre-surgical planning.

METHOD

A retrospective examination of all patients' records that underwent a colloid cyst excision attempt at our institution between 2001 and 2014, and which had a minimum 1-year follow-up was compiled.

RESULTS

Of the 25 patients fulfilling the criteria, we found cysts with a low T2 signal, specifically when combined with high T1 signal, to be significantly correlated with piecemeal, difficult removals. Correlation was also found between high T2 signal cysts and pre-operative hydrocephalus. Among patients that had pre-existing hydrocephalus, those that required a piecemeal removal possessed a strong trend towards a need for subsequent shunting.

CONCLUSIONS

We found specific MRI features suggestive of difficult cyst excision. In a subgroup of patients with pre-operative hydrocephalus and imaging features suggestive of difficult removal, significantly higher rates of shunting were observed. We therefore recommend an open approach in cases of low T2, high T1 signal cysts with a diameter of over 15 mm, or CSF shunting in poor surgical candidates. Smaller cysts, with a low T1 signal, a high T2 signal and pre-operative hydrocephalus, constitute a subgroup in which we recommend endoscopic intervention as the procedure of choice.

A Large Endodermal Cyst with Xanthogranuloma at the Frontal Skull Base, Slowly Recurring with Hemorrhage

A 45-year-old man with a past history of the removal of a degenerated hematoma two times presented with general convulsion. Computed tomography (CT) showed a high-density lobular mass growing from the right frontal skull base and occupying the right frontal lobe. Magnetic resonance imaging (MRI) demonstrated a homogeneously hyperintense mass on T₁-weighted imaging and a homogeneously hypointense mass on T₂- and T₂*-weighted imaging. We removed the lesion, which intraoperatively showed a blackish-brown and jellylike mass with machine oil-like fluid. There was a thin and elastic membrane at the boundary between the mass and degenerated brain tissue, and we removed as much of the membrane as possible. On light microscopy, most parts of the mass consisted of a degenerated hematoma with xanthogranuloma, while the thin and elastic membrane revealed one or two layers of non-ciliated columnar epithelial cells based on thin fibrous tissues with microvessels. Immunohistochemical staining showed that these epithelial cells contained periodic acid-Schiff (PAS)-positive granules, and were positive for cytokeratin (CAM5.2), carcinoembryonic antigen (CEA), and epithelial membrane antigen (EMA). Ultrastructual examination showed numerous microvilli at the surface of non-ciliated cells, and an interdigitation-like, dense adhesion structure. On the basis of pathological findings, the patient was considered to have a large endodermal cyst (EC) at the frontal skull base, probably derived from Seessel’s pouch. We speculate that EC developed inflammatory changes with xanthogranuloma, which caused further damage to the blood vessels and continuous hemorrhage.

Intraoperative Conversion from Endoscopic to Open Transcortical-Transventricular Removal of Colloid Cysts as a Salvage Procedure

OBJECTIVE

 To describe the transcortical-transventricular as an intraoperative salvage procedure and its effect of operative time and outcome.

METHODS

 Thirty-three patients were included in the study. Twenty patients had an endoscopic operation, five had a transcortical-transventricular approach, and eight underwent an interhemispheric approach for resection. Based on common cyst location in the roof of the third ventricle, we propose a simple classification of surgical operative zones based on relationships defined by the anterior column of the fornix, the septal vein, and the medial atrial vein.

RESULTS

 Complete capsule removal was achieved in 35% of endoscopic operations, 100% of transcortical-transventricular operations, and 63% of the interhemispheric operations. Operative time was 176 minutes for endoscopic operations, whereas the operative time for cases that converted to the transcortical-transventricular approach was 190 minutes (p=0.39).

CONCLUSION

 A surgical-based classification of zones within the roof of the third ventricle that can be accessed with microsurgical techniques is proposed. Both endoscopic and microsurgical cyst aspiration and excision remain options. We believe that younger patients, patients with large cysts that fill the third ventricle, or those with recurrence after prior treatment would benefit from open transcortical excision as a safe and effective operative approach using modern image-guided systems. Consent was formally obtained or waived for all subjects present within this study.

Suprasellar dermoid cyst associated with colloid cyst of the third ventricle: Disordered embryogenesis or a mere coincidence?

Intracranial dermoid cyst and colloid cysts of the third ventricle are rare benign congenital lesions of early adulthood. Both lesions are thought to be congenital in origin however association is rare. Only one case of this association has been reported. We report a 22-year-old male with suprasellar dermoid cyst and colloid cyst of the third ventricle presenting simultaneously. Embryogenesis of this association has been discussed.

Xanthogranulomatous colloid cyst of the third ventricle

Colloid cyst in the third ventricle is a common entity, whereas a variant of it, namely xanthogranulomatous, is quite rare. The closest imaging differential diagnosis is a purely third ventricular craniopharyngioma. We herein describe a case of xanthogranulomatous colloid cyst presenting with hydrocephalus.

Olfactory colloid cyst

Colloid cysts are rare intracerebral lesions that are predominantly located in the third ventricle. Extraventricular colloid cysts have only rarely been reported but so far there are no reports of a colloid cyst residing in the olfactory groove. A 74-year-old patient underwent a brain computed tomography scan for a mild head trauma that incidentally revealed a space-occupying lesion near the olfactory groove. Brain magnetic resonance imaging that ensued demonstrated a hyperintense lesion in T1, T2, and FLAIR sequences, without evidence of surrounding brain edema. To evaluate the metabolic status of the lesion, brain single-photon emission computed tomography with 99mTc-Tetrofosmin was then performed, revealing no tracer uptake, a finding consistent with benignity. Due to the diagnostic uncertainty the excision of the lesion was proposed. The patient underwent surgery and intraoperative a cyst was revealed. Furthermore the cyst seemed to erode the dura and due to its location there was an imminent danger for cerebrospinal fluid leak. Therefore a repair of the dura was performed and the cyst was excised totally. Histology verified the presence of a colloid cyst. Colloid cysts should be included in the differential diagnosis of lesions in the anterior fossa and although benign they may have an aggressive presentation by eroding the dura and producing CSF leak.

The role of electron microscopy in the diagnosis of surgical pathology in the central nervous system

Electron microscopy has played an important role in the diagnosis of surgical pathology and the establishment of new tumor entities and variants in the central nervous system. However, the use of ultrastructural analysis of brain tumors has decreased with the advent of immunohistochemistry. I present here my personal experiences and perspective on the role of electron microscopy in surgical neuropathology.

Colloid (Enterogenous) Cyst in the Frontal Lobe-Case Report-

A 60-year-old man presented with a left frontal mass lesion incidentally detected at a health check without apparent symptoms. Computed tomography revealed the lesion as homogeneous high density and magnetic resonance (MR) imaging showed the lesion as hyperintense on T(1)-weighted images, isointense on T(2)-weighted images, and hypointense on diffusion-weighted images. T(1)-weighted MR images with gadolinium showed no enhancement of the mass lesion. Cerebral angiography revealed an avascular area around the left frontal lesion. Total removal of the lesion was achieved through a craniotomy without complications. Histological, immunohistochemical, and electron microscopy examinations established the definite diagnosis of colloid cyst.

Colloid cyst headache

Colloid cysts of the third ventricle are rare intracranial tumors, accounting for 0.5% of intracranial tumors. Colloid cysts represent 2% of gliomas, are more common in men than women, and usually are diagnosed between the third and fifth decades of life. The primary presenting complaint of this disorder is headache. The headaches are described as intermittent, severe and intense, and of short duration and usually are located frontally. The main associated features are nausea and vomiting. The headache can be relieved by lying down, which is unusual for headaches secondary to intracranial tumors. Colloid cysts of the third ventricle are diagnosed by computed tomography or magnetic resonance imaging and treatment is surgical. This rare type of headache disorder is significant because it is associated with sudden death. Recognition of the unusual features of colloid cyst headache may result in decreased mortality in this disorder.

Giant Supratentorial Enterogenous Cyst: Report of a Case, Literature Review, and Discussion of Pathogenesis

OBJECTIVE AND IMPORTANCE

To describe a histologically well-documented adult case of a giant supratentorial enterogenous cyst (EC). Fewer than 15 cases of supratentorial ECs are on record: 8 associated with the brain hemispheres or the overlying meninges, 4 with the sellar region, and 2 with the optic nerve.

CLINICAL PRESENTATION

A 31-year-old woman complained of long-standing mild left brachial and crural motor deficit precipitated by headache and signs of intracranial hypertension. Magnetic resonance imaging revealed a huge cyst overlying the frontoparietal brain.

INTERVENTION

Symptoms were relieved by evacuation of the cyst content by means of a Rickam's reservoir, and the lesion was subsequently removed in toto. Histological and immunohistochemical examination of the cyst wall clearly established the enterogenous nature of its epithelium. Follow-up for up to 2 years after intervention showed no sign of recurrence, and symptoms, including treatment-resistant seizures in the postoperative period, have entirely subsided.

CONCLUSION

Supratentorial ECs, distinctly rare in adult patients, may in some cases present as giant lesions. Total removal seems to be curative once careful examination has eliminated the possibility of a metastasis from an unknown primary. A correct histological diagnosis is important because, in contrast to other benign cysts of similar location and size, ECs may be prone to intraoperative dissemination.

Benign cysts in the central nervous system: Neuropathological observations of the cyst walls

A diverse variety of benign cysts exist in the CNS. Advances in diagnostic radiology have facilitated diagnoses and surgical intervention in many patients with CNS cysts. However, a fundamental understanding of the pathological features of these lesions is clinically vital. From an etiological point of view, the cysts can be divided into two groups. The first includes lesions that arise from within the CNS and may be static structures such as cavities arising from infarcts and other destructive processes while other lesions such as arachnoid cysts, ependymal cysts, cystic hemangioblastoma, cystic cerebellar astrocytoma and infectious processes, are progressive. The second group of cysts arise from the intrusion of non-nervous system tissue into the neuroaxis and are usually midline. They are frequently expanding congenital lesions although some become symptomatic only in adults. Examples include teratomas, dermoid cysts, epidermoid cysts, craniopharyngiomas, Rathke's cleft cysts, and other epithelial cysts presumably derived from the upper respiratory or intestinal tract. Chick embryos exposed to lead have been used as a model of cyst formation.

Colloid-like cyst located in the prepontine region

BACKGROUND

The term "colloid cysts" refers to nonneoplastic lesions located in the anterior part of the third ventricle. However, cysts morphologically identical to colloid cysts are found, albeit extremely rarely, through the neuraxis.

CASE DESCRIPTION

We report a case of a 44-year-old man with a short history of headache and 5 years of bilateral hearing loss. Computed tomography (CT) and magnetic resonance imaging (MRI) scans showed an oval lesion located at the anterior surface of the pons. The tumor was excised through a right pterional transsylvian approach. Postoperatively, the hearing deficit remained unchanged. Otherwise, the patient made an excellent recovery. Histopathological examination showed a colloid-like cyst.

CONCLUSIONS

Colloid-like cysts growing in the prepontine region are extremely rare. To date, only two similar cases have been reported in the literature. Patients present with headaches, hearing loss, or blurred vision.

Intraepithelial carcinoma arising in an endodermal cyst of the posterior fossa

Endodermal cysts of the central neuraxis are benign, non-neoplastic epithelium-lined cysts arising from endodermal tissue that have been displaced early in fetal life. Intracranial endodermal cysts are rare and usually located in the posterior fossa. The present study involves a 36-year-old man with a typical epithelial cyst in the posterior fossa. Microscopically, the cyst has a simple columnar epithelium with mucus-producing cells, containing an area composed of dysplastic epithelium with evidence of an intraepithelial carcinoma. The atypical cells have a high proliferative fraction demonstrated by Ki-67 immunostain. Based on these findings, the authors view this case as evidence of a malignant transformation of a classic endodermal cyst. The clinicopathologic features and a review of the literature are discussed.

Spontaneous rupture of a presumed colloid cyst of the third ventricle--case report

An 83-year-old man presented with gait disturbance, dementia, and urinary incontinence that had progressed over 2 months. Computed tomography (CT) of the brain revealed hydrocephalus due to a well-demarcated, round hyperdense mass in the third ventricle, which was not enhanced by contrast agent. Ten days after the initial evaluation, CT revealed that the cyst in the third ventricle had disappeared. Magnetic resonance imaging revealed spontaneous rupture of the lesion and remnants of cyst wall anchored to the anterior roof of the third ventricle. Thereafter, the symptoms of hydrocephalus subsided. However, 6 months later the patient's condition gradually deteriorated and the ventricles dilated without any evidence of tumor regrowth. Surgical intervention was not performed as the family of the patient withheld consent. The natural history of colloid cysts of the third ventricle remains unclear. Spontaneous rupture of a presumed colloid cyst of the third ventricle should be considered when planning treatment.

Colloid cyst of the third ventricle: a clinical review of 39 cases

This paper is a retrospective review of all patients treated for a colloid cyst of the third ventricle at Royal Prince Alfred Hospital over an 18-year consecutive period. Our experience is fairly typical compared with other published series. Colloid cys ts made up 1.6% of tumours treated by the neurosurgical unit. Patients presented with non-specific neurological symptoms and signs, commonly suggestive of raised intracranial pressure. Microsurgical excision was carried out via the transcallosal route in 34 cases and the transfrontal approach in four cases. There was no apparent difference in results from the different surgical approaches. In 86% of patients reviewed after more than 6 months good long term outcome was achieved. These benign tumours can be safely cured if the diagnosis is made early and the cyst removed by careful microsurgical techniques.

Solid-calcified colloid cyst of the third ventricle

We report a 65-year-old female with a solid-calcified colloid cyst in the third ventricle that was demonstrated on computed tomography scan and magnetic resonance images. The lesion was surgically excised using the anterior transcallosal-transforaminal approach. Complete preservation of the surrounding neural and vascular structures was achieved.

Tumors of the choroid plexus

Choroid plexus tumors are rare intraventricular papillary neoplasms derived from choroid plexus epithelium, which account for only between 0.4-0.6% of all intracranial and 2-3% of pediatric neoplasms. Plexus papillomas outnumber choroid plexus carcinomas by a ratio of 5:1 and around 80% of choroid plexus carcinomas arise in children. Plexus tumors are most common in the lateral and fourth ventricles; while 80% of lateral ventricle tumors present in children, fourth ventricle tumors are evenly distributed in all age groups. Clinically, choroid plexus tumors tend to cause hydrocephalus and increased intracranial pressure. Histologically, choroid plexus papillomas correspond to WHO grade I, choroid plexus carcinomas to WHO grade III. Immunohistochemically, cytokeratins and vimentin are expressed by virtually all choroid plexus papillomas and most choroid plexus carcinomas while transthyretin and S-100 protein are present in 80-90% of cases, less frequently, though, in choroid plexus carcinomas. Glial fibrillary acidic protein can be found focally in about 25-55% of choroid plexus papillomas and 20% of choroid plexus carcinomas. The mean Ki67/MIB1 labeling index for choroid plexus papillomas is 1.9%, for choroid plexus carcinomas 13. 8%. Choroid plexus papillomas typically show hyperdiploidy with gains particularly on chromosomes 7, 9, 12, 15, 17, and 18 while one choroid plexus carcinoma showed rearrangements of chromosomes 7p11-12, 9q11-12, 15q22, and 19q13.4. Choroid plexus papillomas can usually be cured by surgery alone with a 5-year survival rate of up to 100% with occasional recurrences while choroid plexus carcinomas grow more rapidly and have a less favorable outcome with a 5-year survival rate of 26-40%.

A theory on the natural history of colloid cysts of the third ventricle

OBJECTIVE

Patients with third ventricular colloid cysts typically are diagnosed when they develop symptoms related to cerebrospinal fluid (CSF) obstruction at the foramen of Monro. However, the clinical and neuroimaging characteristics related to symptom development are poorly understood.

METHODS

From January 1974 to June 1998, 155 patients with newly diagnosed colloid cysts were managed at our center. Eighty-seven patients (56%) were thought to have tumor-related symptoms, and they underwent surgery (resection, n = 74; ventriculoperitoneal shunting, n = 11; stereotactic aspiration, n = 2). Sixty-eight patients (44%) had colloid cysts thought to be asymptomatic, and observation with serial neuroimaging was recommended. Recursive partitioning was used to examine the association of patient and tumor characteristics with the development of cyst-related symptoms.

RESULTS

Univariate analysis comparing symptomatic and asymptomatic patients revealed four factors associated with cyst-related symptoms: 1) younger patient age (44 yr versus 57 yr; P < 0.001); 2) cyst size (13 mm versus 8 mm; P < 0.001); 3) ventricular dilation (83% versus 31%; P < 0.001); and 4) increased signal on T2-weighted magnetic resonance images (44% versus 8%; P = 0.001). All four variables remained significant in a multivariate logistic regression model: patient age (P = 0.04; odds ratio, 1.0); cyst size (P = 0.04; odds ratio, 1.2); ventricular dilation (P = 0.02, odds ratio, 7.2); and increased signal on T2-weighted magnetic resonance images (P = 0.04; odds ratio, 2.7). The most significant variable was ventriculomegaly (yes versus no). Patients with normal-sized ventricles (n = 62) were further categorized by cyst size (< or = 10 mm versus > 10 mm). For patients with enlarged ventricles (n = 93), patient age (< or = 50 yr versus > 50 yr) was the most important variable. Patients older than 50 years also were split with respect to cyst size; patients aged 50 years or younger with enlarged ventricles were not affected by cyst size. The percentage of patients with cyst-related symptoms was 12, 50, and 85% in the three final patient classes, respectively. Multivariate analysis including the patient classes resulted in removal of the other significant variables from the model, whereas the patient classes remained significant (P < 0.0001; odds ratio, 6.3) for predicting patients with cyst-related symptoms.

CONCLUSION

The patient and neuroimaging characteristics of the different patient classes support a theory on the natural history of colloid cysts. Patients with third ventricular colloid cysts become symptomatic when the tumor enlarges rapidly, causing CSF obstruction, ventriculomegaly, and increased intracranial pressure. Some cysts enlarge more gradually, however, allowing the patient to accommodate the enlarging mass without disruption of CSF flow, and the patient remains asymptomatic. In these cases, if the cyst stops growing, the patient can maintain a steady state between CSF production and absorption and may not require neurosurgical intervention.

Familial colloid cysts of the third ventricle: case report

OBJECTIVE AND IMPORTANCE

Familial colloid cysts of the third ventricle are very rare. This is the largest family reported and the first in which all affected members are female and all members have been screened. Screening led to the diagnosis of an asymptomatic case of a colloid cyst of the third ventricle, and the management of that lesion is discussed.

CLINICAL PRESENTATION

A mother and two daughters who were diagnosed with colloid cysts of the third ventricle, from a family containing four sisters, three brothers, and the father, are presented.

INTERVENTION

The index patient (Patient 2) underwent computed tomographic scanning-guided stereotactic transcallosal excision of her colloid cyst. Her siblings and her father were screened using magnetic resonance imaging as well as computed tomographic scanning. Cytogenetic analysis of blood samples obtained from the patient and her family revealed no chromosomal abnormalities.

CONCLUSION

Screening is of value for families in which two or more members are affected. The management of asymptomatic cases is influenced by the lesion size and the age and fitness of the patient.

Familial fatal and near-fatal third ventricle colloid cysts

BACKGROUND

Despite having a presumed congenital origin, familial cases of colloid cysts have been reported only rarely. The first case of a brother and sister with colloid cysts is reported here, and the relevant literature is reviewed.

METHODS

A 25-year-old man presented with a 24-h history of headache and vomiting. He rapidly became unconscious and fulfilled the criteria for brain death on arrival at hospital. No surgical intervention was performed.

RESULTS

The patient's sister presented at the age of 41 with headaches and rapidly became unconscious. The sister had urgent bilateral ventriculostomies. followed by transcallosal removal of a colloid cyst.

CONCLUSIONS

These cases support the hypothesis that colloid cysts are congenital lesions and provide some evidence of a possible genetic predisposition to their formation. Sudden death remains a real risk for patients harbouring a colloid cyst.

Angiogenic histogenesis of stromal cells in hemangioblastoma: ultrastructural and immunohistochemical study

Controversy regarding the origin of characteristic stromal cells (SC) is responsible for the placement of hemangioblastoma as a single entity in the category of "tumors of uncertain histogenesis" in the current WHO classification of brain tumors. This subclassification of hemangioblastoma is, to a large extent, a consequence of a remarkable antigenic heterogeneity of SC demonstrated in many, often contradictory immunohistochemical studies. In contrast, most of the electron microscopic studies demonstrated a number of features indicating angiogenic nature of SC and, therefore, hemangioblastoma. This study reevaluated the histogenesis of SC, applying immunohistochemistry as well as electron microscopy and immunoelectron microscopy. Immunohistochemical studies confirmed most of the previous results indicating a very frequent expression of vimentin, S-100 protein, neuron-specific enolase, and cytokeratins. SC were less commonly immunoreactive for desmin, factor XIIIa, and Ricinus communis lectin receptors, and only occasionally for factor VIII and Ulex europeus lectin. They were negative for other markers of endothelial, neuronal, glial, neuroendocrine, and smooth muscle differentiation. Approximately 1% of SC showed Ki67 immunoreactivity, indicating their slight proliferative activity, consistent with the benign nature of the tumor. In contrast to the inconclusive results of the immunohistochemistry, electron microscopy demonstrated a clear relationship of SC to endothelial cells, smooth muscle cells, and pericytes. Occasional SC were found within the vascular lumina. SC often showed intracellular caveolae consistent with the formation of early capillary lumina. Moreover, occasional SC contained small Weibel-Palade bodies positive for factor VIII in immunoelectron microscopy. SC represent a heterogeneous population of abnormally differentiating mesenchymal cells of angiogenic lineage, with some morphological features of endothelium, pericytes, and smooth muscle cells. Occurrence of SC in hemangioblastoma could be related to a limited ability of angioformative stromal cells to develop an architecture of capillary lumina integrated with the vascular network of the tumor. Hemangioblastoma should be reclassified and included together with other vascular tumors of the central nervous system.

Natural history of asymptomatic colloid cysts of the third ventricle

OBJECT

To determine the natural history of colloid cysts of the third ventricle in patients in whom the cysts were incidentally discovered, the authors retrospectively reviewed cases observed during the modern neuroimaging era (1974-1998).

METHODS

During this 25-year interval, 162 patients with colloid cysts were examined and cared for at our center. Sixty-eight patients (42%) were thought to be asymptomatic with regard to their colloid cyst and observation with serial neuroimaging was recommended. The mean patient age was 57 years at the time of diagnosis (range 7-88 years) and the mean cyst size was 8 mm (range 4-18 mm). Computerized tomography scanning revealed a hyperdense cyst in 49 (84%) of 58 patients. Three patients were excluded from the study because they died of unrelated causes within 6 months of scanning and seven patients were lost to follow-up review. Clinical follow-up evaluation was available at a mean of 79 months (range 7-268 months) in the remaining 58 patients. The numbers of patients who participated in follow-up review at 2, 5, and 10 years after diagnosis were 40, 28, and 14, respectively. The incidences of symptomatic progression related to the cyst were 0%, 0%, and 8% at 2, 5, and 10 years, respectively. No patient died suddenly during the follow-up interval. Two (6%) of 34 patients in whom follow-up imaging was performed either exhibited cyst growth (one patient) or experienced hydrocephalus (one patient) at a mean of 41 months after diagnosis (range 4-160 months).

CONCLUSIONS

Patients in whom asymptomatic colloid cysts are diagnosed can be cared for safely with observation and serial neuroimaging. If a patient becomes symptomatic, the cyst enlarges, or hydrocephalus develops, prompt neurosurgical intervention is necessary to prevent the occurrence of neurological decline from these benign tumors.

Rare occurrence of intracerebellar colloid cyst. Case report

Colloid cysts are rare intracerebral lesions that are preferentially encountered within the third ventricle. There are only a few reports in which colloid cysts are described in other locations such as the fourth ventricle. A symptomatic intracerebellar colloid cyst in a 45-year-old woman is described. The patient presented with headache, gait disturbance, and nausea. Neuroradiological imaging revealed compression of the fourth ventricle, hydrocephalus, and an intracerebellar cystic lesion measuring 4 x 5 cm that had a small peripheral solid portion. The cyst was successfully removed via a paramedian suboccipital approach. Postoperatively, the patient recovered quickly. The findings in the present report represent an additional example of the broad spectrum of cystic lesions encountered in the cerebellum.

Aggressive enterogenous cyst with extensive craniospinal spread: case report

OBJECTIVE AND IMPORTANCE

Considered benign and malformative in nature, enterogenous cysts are predominantly spinal lesions. Although recurrences have been reported, especially in the rare intracranial examples, craniospinal dissemination has never been described.

CLINICAL PRESENTATION

We report a 63-year-old woman who presented 16 years previously with a histologically typical enterogenous cyst of the cerebellum. Fourteen years after its incomplete excision, numerous supratentorial, infratentorial, and spinal subarachnoid cysts were detected. A histological examination revealed multiple enterogenous cysts without evidence of malignancy. Ki-67 (MIB-1) proliferative indices were less than 1% in all except one specimen, wherein it was 4%; immunohistochemistry demonstrated rare p53 protein overexpression.

INTERVENTION

During the last 2 years, four subtotal resections of spinal enterogenous cysts have been performed for progressive paraplegia, pain, paresthesia, and bladder dysfunction. Considering the multiple recurrences and progressive neurological deficits, craniospinal radiation therapy was given.

CONCLUSION

To our knowledge, this is the first report of widespread craniospinal dissemination associated with the incomplete resection of an enterogenous cyst. Although a rare complication, it emphasizes the advantages of early, aggressive surgery.