Epithelial cysts in the central nervous system, characteristic expression of cytokeratins in an immunohistochemical study

Suprasellar colloid cyst: an unusual location

BACKGROUND

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, brainstem, cerebellum, and suprasellar region.

CASE DESCRIPTION

A young woman presented with headaches for 1 year and an episode of generalized tonic, clonic seizures 1 week ago. She had bitemporal visual field cuts on examination. Imaging showed an hyperdense suprasellar lesion that was isointense on T1-weighted magnetic resonance imagings, profoundly hypointense on T2-weighted images, and did not show any enhancement on contrast magnetic resonance study at follow-up. It showed no restriction on diffusion-weighted imaging. A pteronal craniotomy and total excision of the lesion was done and the patient recovered well with no further neurological deficits. Pathology was consistent with a colloid cyst.

CONCLUSIONS

Colloid cysts are rarely found in a suprasellar location. Such a rare diagnosis has to be considered in the differential diagnosis in patients who present with a suprasellar cystic lesion.

A case of split notochord syndrome: an adult with a spinal endodermal cyst mimicking an intramedullary tumor

Intraspinal endodermal cysts are very rare congenital cysts, usually composed of a thin-walled cyst the lining of which mimics gastrointestinal or respiratory epithelium. Diagnosis is usually established during the first or second decade of life. These cysts are frequently associated with vertebral or spinal cord abnormalies and dual malformation with mediastinal or abdominal cysts. Collectively, they are called split notochord syndrome. The authors describe their experience in the treatment of a 57-year-old man having an endodermal cyst mimicking an intramedullary tumor at the level of Th1-2. He was admitted to our institution for evaluation of an intraspinal mass diagnosed by MRI at a local hospital after experiencing temporary numbness and weakness of the lower left extremity. T1-weighted sagittal MRI demonstrated the lesion with signal intensity iso- to slightly hypointense to the spinal cord without enhancement after administration of gadolinium. Although T2-weighted sagittal images demonstrated as hyperintense to the spinal cord, axial images revealed a passage between the mass and subarachnoid space. We could not completely rule out the presence of an intramedullary tumor and undertook a laminectomy with a posterior approach. Histopathological analysis revealed an endodermal cyst and the authors found syringomyelia, which was clearly separated from the cyst in the preoperative sagittal MRI and intraoperative ultrasonography study. To the best of our knowledge, this is the first report in the English literature of a thoracic endodermal cyst requiring differential diagnosis from a spinal cord tumor.

Endodermal cyst anterior and anterolateral to the brainstem. A report of an experience with seven cases

We report our experience with seven cases of endodermal cysts located anterior and anterolateral to the brainstem. The ages of the patients ranged from 10 to 35 years. There were three males and four females. The cysts had characteristic imaging features, and contained fluid having a 'greenish-yellow pus-like' hue and consistency varied from thin watery fluid to colloid gel like material. The capsule of the tumour was relatively thin. A radical resection of the cyst contents was done in all cases. Because of the thin nature of capsule, wide extensions and intimate relationship with critical nerves and vessels, complete resection of the cyst wall was possible only in one case, whilst in others the wall was partially resected. All patients showed a rapid symptomatic and neurological recovery. During the average follow-up period of 53 months, there has been no recurrence in the cyst and all patients are leading normal lives. In this presentation, the clinical and radiological features and surgical management of endodermal cysts are discussed and the relevant literature is briefly reviewed. It appears that evacuation of the cyst contents and partial resection of the cyst wall could be a safe treatment option in these cases.

Neurenteric cyst with xanthomatous changes in the prepontine area: unusual radiological findings

Preoperative diagnosis of neurenteric cysts can be difficult because the imaging findings of a neurenteric cyst may be similar to those of an arachnoid cyst. The authors report a case of a neurenteric cyst with xanthomatous changes in the prepontine area. This 4-year-old girl was admitted to their institution with intermittent neck pain and vomiting. Computed tomography showed a hypodense mass in the prepontine area. Magnetic resonance imaging showed a cystic lesion measuring approximately 4 x 3 cm. The brainstem was displaced posteriorly, and the cisterns in both cerebellopontine angles were widened. The signal intensity of the cyst was similar to that of cerebrospinal fluid. Adjacent to the basilar artery there was a solid component of the mass that enhanced after administration of Gd. Intraoperatively, the authors found a cystic mass containing clear fluid with a yellowish solid nodule. On the basis of histopathological findings, the lesion was diagnosed as a neurenteric cyst with xanthomatous changes.

Comparative immunohistochemical assessment of craniopharyngioma and related lesions

Craniopharyngiomas (CP), Rathke's cleft cysts (RCC), and sellar xanthogranulomas (XG) are closely related lesions. As expression of cytokeratins 8 (CK8) and 20 (CK20) was reported in RCC but not in CP, the present study investigates the reproducibility of immunohistochemical distinction between CP and RCC, attempting to identify the relationship of XG to these lesions. A comparative study of 55 patient specimens (25 CP, 28 RCC, and 2 XG) was analyzed for the histological features of xanthomatous changes and squamous metaplasia, and expression of CK8 and CK20. In the 25 CP cases, xanthomatous changes were seen in 5 (20%), with CK8 reactivity demonstrated in all 25 cases. A prominent xanthomatous component was identified in 13 of 28 RCC (46%), and squamous metaplasia was seen in 11 (39%), 9 of which also contained xanthomatous features. CK8 reactivity was demonstrated in all 28 RCC cases, whereas CK20 was seen only in 9 cases (32%). Of the two cases diagnosed as XG, none contained epithelium, and immunohistochemistry for cytokeratins was not observed. Overall, differential expression of cytokeratins cannot reliably distinguish CP from RCC. Furthermore, expression of CK20 in RCC is generally seen within a background of prominent squamous metaplasia and reactive xanthomatous changes.

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.

Endodermal Cyst Ventral to the Lower Brain Stem-Case Report-

A 28-year-old woman presented with a rare case of endodermal cyst located ventral to the lower brain stem manifesting as recurrent aseptic meningitis. Computed tomography and magnetic resonance imaging demonstrated a cystic mass located ventral to the lower brain stem and extending from the prepontine to the upper cervical (C-2) cistern. The lesion was totally removed through a retrosigmoid craniotomy and C1-2 hemilaminectomy. Histological and immunohistochemical examination showed the cyst was derived from the endoderm. The histological diagnosis was endodermal cyst. Early diagnosis and surgical removal are important for patients with these cysts.

Endodermal cyst of the cervical spinal cord with associated partial fusion of the vertebrae

A case of a 43-year-old woman with an intradural endodermal cyst at the C4 spinal cord level is presented. The lesion manifested with progressive neck pain and weakness of lower extremities. The presumptive diagnosis of extramedullary benign cystic lesion was established after MRI examination. Coexisting partial fusion of the C5-C6 vertebral bodies was found on X-ray films. The patient was cured by resection of the cyst wall, performed by laminectomy. Pathological examination revealed a cyst wall lined with ciliated cuboidal cells, resembling the respiratory epithelium. Immunohistochemistry demonstrated cytokeratin and epithelial membrane antigen expression in the lining of the cyst. Endodermal cyst should be considered in the differential diagnosis of intraspinal cystic lesions, especially those associated with vertebral anomalies.

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.

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.

Intracranial neurenteric cysts: a report of two cases

Neurenteric or enterogenous cysts are rare, congenital, benign lesions of the central nervous system. Not more than 35 case reports of neurenteric cysts occurring in the cranial cavity have been documented. We describe two cases of intracranial neurenteric cysts.

Histological changes in the pituitary gland and adenomas following radiotherapy

To elucidate histological changes in the pituitary gland and adenomas following radiotherapy, two irradiated pituitary glands and seven irradiated non-functioning adenomas were studied. The latter included four cases with conventional radiation (CR) and three cases with radiosurgery: two with gamma knife radiosurgery (GKR) and one with stereotactic fractionated radiotherapy (SRT). The specimens were obtained 10 months to 10 years (mean 58 months) after the radiotherapy. Irradiated pituitary glands showed diffuse fibrosis in the adenohypophysis, whereas irradiated adenomas showed either mild or no fibrosis in five CR/SRT cases and diffuse thick hyaline deposits in two GKR cases. No necrosis was observed. Stellate-shaped S-100 protein-positive cells were greater in number in the irradiated pituitary glands than in the normal glands. Pituitary cells with dense granular reactivity for mitochondrial protein, cytochrome oxidase, and Mn-SOD, mimicking oncocytes, were greater in number in the irradiated adenohypophysis but did not show any change in cell size. Many irradiated pituitary cells and some irradiated adenoma cells were densely positive with anticytokeratin 1,5,10,14 antibody whereas non-irradiated counterparts were negative. In adenomas, MIB-1 labeling index remained unchanged after the radiation. The results may indicate that radiation-induced fibrosis was associated with an increased number of folliculo-stellate cells, mitochondrial dysfunction, and squamous metaplasia. These findings were prominent in irradiated pituitary cells and may participate in delayed pituitary hypofunction following radiotherapy. In irradiated adenoma cells, similar findings were observed but diffuse fibrosis was absent. The histological changes were more intensive in adenomas following GKR than those following CR.

Endodermal cysts of the posterior fossa. Report of three cases and review of the literature

The pathogenesis of endodermal cysts of the posterior fossa is still incompletely understood. The authors reviewed three new cases and those reported in the literature to clarify the clinical, pathological, radiological, and surgical characteristics of these lesions. A total of 49 cases were reviewed. Details on demographic profiles, clinical characteristics, histopathological and radiological features, and surgical methods were collected. These cysts have a predominance in male patients (61%) and can occur at any age (birth-77 years). In patients with posterior fossa endodermal cysts there is a bimodal age distribution and headache is the most frequent complaint. On immunohistopathological examination, endodermal cysts were reactive for epithelial membrane antigen and for keratin immunostains whenever the latter were tested. The cysts were reactive for carcinoembryonic antigen in nine of 11 cases. Endodermal cysts were located anterior to the brainstem in 51% of cases and in the fourth ventricle in 21% of cases. They frequently appeared hypodense on computerized tomography scans, and in five cases, the lesion was missed. The cyst's appearance on magnetic resonance imaging is variable. Resection was complete in 19 cases and partial in 11; marsupialization was achieved in two cases. Three recurrences have been reported. Total excision with preservation of neurological function should be the goal. Cranial base approaches are helpful for surgical access in selected examples of these lesions.

Do the suprasellar neurenteric cyst, the Rathke cleft cyst and the colloid cyst constitute a same entity?

Two cases of entirely suprasellar cysts are reported. Total surgical removal was performed in both cases. Pathological and immunohistochemical profiles were consistent with neurenteric cysts, Rathke's cleft cysts or colloid cysts and was also in keeping with an endodermal origin. It is now admitted that these three kinds of cysts share similar histological and immunohistological features. We propose an hypothesis of common embryological origin from endodermal remnants.

Enterogenous cyst of the orbital apex and superior orbital fissure

BACKGROUND

Enterogenous cysts of the central nervous system are rare congenital tumors with a single layer of mucin-secreting epithelial cells resembling gastrointestinal epithelium. The tumor is located most commonly at lower cervical and cervicothoracic spinal levels; only 22 intracranial cases have been reported. To the authors knowledge, this entity has not been described in the orbit.

METHODS

A 23-year-old woman with painful loss of vision and ophthalmoplegia in the left eye was treated with oral and intravenous corticosteroids for presumed orbital inflammation. After a cystic lesion in the left orbital apex was demonstrated on computed tomographic scan and magnetic resonance imaging, various diagnoses, including optic nerve tumor, granulomatous inflammation, lymphoma, vascular anomaly, and pseudotumor, were considered until transcranial biopsy established the correct diagnosis. The tumor subsequently recurred twice.

RESULTS

More than 3 years after the last recurrence, the patient has no pain but had unilateral optic atrophy, significant visual field loss, limited motility, and an anesthetic cornea in the left eye.

CONCLUSION

The diagnosis of enterogenous cyst is difficult without adequate biopsy because the radiologic and clinical presentation of this rare tumor may be confused with other lesions. Previous attempts to explain intracranially placed enterogenous cysts offer no explanation for an orbital occurrence nor do they adequately describe a mechanism for an intracranial location in general. An embryologically based explanation that takes into account the occurrence of this entity from the caudal to rostral extent of the neuraxis is described. This theory suggests that the orbit is the most rostral possible location for an enterogenous cyst.

Epithelial cystic lesions of the sellar and parasellar region: a continuum of ectodermal derivatives?

Cystic epithelial lesions of the sellar and parasellar region are classified on the basis of histology and location into Rathke's cleft cysts, epithelial cysts, epidermoid cysts, dermoid cysts, and craniopharyngiomas. A retrospective review of the clinical presentation, radiological findings, and histology was performed on 19 such lesions, and a survey of the literature pertinent to the classification, clinical presentation, and embryology of these lesions was conducted. Presentation was nonspecific and not predictive of histology. Imaging studies were generally useful in distinguishing these tumors, with the exception of Rathke's cleft cysts, suprasellar epidermoid cysts, and craniopharyngiomas, which frequently could not be differentiated. On microscopic examination, most lesions fit into distinct categories; however, overlap was common among all and some could not be definitively categorized by histological criteria. Evidence supportive of an ectodermal ancestry for sellar and parasellar epithelial-lined cystic lesions is presented. Based on the current findings and a review of the literature, it is suggested that these lesions represent a continuum of ectodermally derived cystic epithelial lesions.

An epithelial cyst of the suprasellar region

A case of a 26 year old woman with increasing headaches due to a suprasellar cyst is described. Histology was consistent with an epithelial cyst with features resembling both Rathke's cleft cysts and enterogenous cysts. The differential diagnosis and treatment of suprasellar cysts is discussed.

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

In an effort to shed light upon the nature of the colloid cyst, the immunohistochemical properties of 21 examples of this lesion were compared with those of other neuraxial cysts and choroid plexus epithelium. The neuraxial cysts included the following: eight Rathke's cleft cysts, 25 pituitaries containing follicular cysts of the pars intermedia, and four enterogenous cysts. Fifteen examples of normal choroid plexus and 12 choroid plexus papillomas were studied as well. These lesions were examined for localization of the following antigens: cytokeratins, epithelial membrane antigen, secretory component, carcinoembryonic antigen, prealbumin, vimentin, glial fibrillary acidic protein (GFAP), S-100 protein, neuron-specific enolase, 68-kD neurofilament protein, chromogranin, serotonin, and lysozyme, and with Leu-7 monoclonal antibodies. Five colloid cysts were immunostained with monoclonal antibodies that were specific for Clara-cell antigens and surfactant, respectively. Sugar moieties were localized using Ulex europaeus I, and Ricinus communis agglutinin I lectins. All Rathke's cleft cysts and follicular cysts of the pars intermedia as well as three selected colloid cysts were examined for pituitary hormones. The epithelial cells of colloid and enterogenous cysts, as well as those lining follicular and Rathke's cleft cyst, showed uniformly strong reactivity for cytokeratins, epithelial membrane antigen, secretory component, and vimentin, and bound Ulex europaeus lectin. Occasional cells in colloid cysts were positive for Clara cell-specific antigens. Reaction for carcinoembryonic antigen was present on the apical surface of scattered cells of colloid, follicular, and Rathke's cleft cysts. Many cells of follicles in the pars intermedia as well as individual cells of five Rathke's cleft cysts were also immunoreactive for chromogranin, S-100 protein, GFAP, and pituitary hormones. Colloid and enterogenous cysts were negative for prealbumin, S-100 protein, GFAP, and neuron-specific enolase; in all but a few instances, they failed to bind Ricinus communis agglutinin. In contrast, normal choroid plexus and choroid plexus papillomas were positive for prealbumin, S-100 protein, neuron-specific enolase, cytokeratin, vimentin, and Ricinus communis agglutinin receptors; they lacked Ulex europaeus lectin, 56/66-kD cytokeratins, and epithelial membrane antigen. Unlike normal choroid plexus, choroid plexus papillomas were often GFAP-positive. All tissues studied were nonreactive for lysosome, serotonin, and neurofilament, and with Leu-7 antibodies. This study indicates that the immunophenotype of epithelium lining colloid cysts is similar to that of other cysts showing endodermal or ectodermal differentiation and to respiratory tract mucosa. Epithelium of colloid cysts is immunohistochemically different from that of normal or neoplastic choroid plexus. These findings indicate an endodermal rather than neuroepithelial nature for colloid cysts.

Prepontine cyst lined by respiratory epithelium with squamous metaplasia: immunohistochemical and ultrastructural study

An 8.5-year-old female presented with multiple episodes of aseptic meningitis and was found to have a cystic lesion in the prepontine region. Microscopic examination revealed a respiratory-type epithelium with squamous metaplasia. Like its normal analogue in the respiratory tract, the epithelium of these intracranial cysts can undergo squamous metaplasia when chronically irritated. The ultrastructural and immunohistochemical characteristics of the transition from ciliated epithelium to squamous metaplasia are described.

Folliculostellate cells of the pituitary

In addition to the hormone-producing granulated cells, the so-called folliculostellate (FS) cells of the adenohypophysis represent a population of nongranulated cells extensively described in a large number of species. They show distinctive morphological features including a star shape with thin cytoplasmic projections extending between granulated cells and well-developed junctional complexes. FS cells are joined together surrounding irregular microcavities and project microvilli into the lumina. The immunocytochemical localization of S-100 protein, glial fibrillary acidic protein, and vimentin constitutes a reliable and easy method for investigating their presence and distribution in the normal pituitary gland and in pituitary adenomas. Although the expression of glial cell markers raised the hypothesis of a neuroectodermal origin of FS cells, most evidence supports that they derive from the epithelium of the Rathke's pouch, as do granulated adenohypophyseal cells. Morphological studies indicate that FS cells are involved in phagocytosis and possess sustentacular functions. Investigations using cell cultures show that FS cells play important roles in the paracrine regulation of adenohypophy-seal secretion by their ability to liberate several growth factors and regulate the ionic composition of the extracellular fluid. Further research using novel immunocytochemical markers and ceil culture techniques may clarify the origin and the role of this enigmatic cell type in the normal and pathological pituitary gland.