Cauda equina tumor with ependymal and paraganglionic differentiation.

We describe the case of a 31-year-old woman who was first treated for a pigmented choroid plexus papilloma of the fourth ventricle. Ten year later, she developed a new tumor in the region of the cauda equina. This second neoplasm contained areas of papillary ependymoma that displayed phosphotungstic acid hematoxylin-positive glial fibers and immunoreactivity for glial fibrillary acidic and S-100 proteins. Areas of ependymoma merged with others that displayed the appearance of a paraganglioma, including lobules and nests of chief cells immunoreactive for neuron-specific enolase, synaptophysin, chromogranin, and serotonin. Satellite cells, but not chief cells, stained for glial fibrillary acidic and S-100 proteins. Electron microscopy showed features of both ependymal and paraganglionic differentiation, including intercellular lumina with microvilli, junctional complexes, cell processes with closely packed filaments, and dense core granules. Our case represents a rare example of a cauda equina neoplasm with simultaneous ependymal and paraganglionic differentiation. To our knowledge, this is the first described example of a tumor of this region showing features of both ependymoma and paraganglioma.     

The cytologic findings in choroid plexus carcinoma: report of a case with differential diagnosis

Choroid plexus carcinoma is a rare tumor of the choroid plexus that shows frank cytologic features of malignancy including frequent mitoses, increased cellularity, nuclear pleomorphism, loss of papillary architecture, and necrosis. It occurs predominantly in the pediatric population and is associated with a poor prognosis. We report the cerebrospinal fluid and intraoperative squash preparation cytologic findings of a case of choroid plexus carcinoma arising in the lateral ventricle of a 16-year-old girl who developed tumor recurrence in cerebrospinal fluid 6 years after initial resection. To the best of our knowledge, there are only a few reports in the English literature describing the cytologic features of choroid plexus carcinoma. Relevant differentials and the usefulness of ancillary studies in diagnosis are also discussed.     

A case report of a choroid plexus carcinoma spontaneously occurring in the right lateral ventricle of a 14-week-old, female Donryu rat

We encountered a brain tumor arising in the right lateral ventricle of a 14-week-old, female Donryu rat and investigated its histological and immunohistochemical characteristics. Macroscopically, the tumor appeared as a grayish mass with a size of 10 mm in diameter, present in front of the right hemicerebrum and well circumscribed on the cut surface. Histological examination revealed the tumor to be a hypercellular mass occupying the front part of the right lateral ventricle and expanding into the area in front of the hemicerebrum, continuing to the ependymal area at its edge. The tumor was constituted by columnar- or pleomorphic-shaped, highly atypical cells of epithelial origin surrounding fibrovascular cores as single or multiple cell layers. Growth was papillary with high proliferating activity. Immunohistochemically, the tumor cells proved positive for cytokeratin but negative for vimentin, S100 protein or glial fibrillary acidic protein, a profile characteristic for the epithelial cells of the choroid plexus, whereas the ependymal cells were found to be positive for all 4 items. In conclusion, the present tumor was diagnosed as a rat choroid plexus carcinoma, only the third such case to be reported in the world literature, with particular features.     

Pigmented choroid plexus papilloma

A pigmented choroid plexus papilloma was found in the left lateral ventricle of a 15-year-old white boy with a 10-year history of seizures. Grossly the lesion appeared finely lobular, orangish brown, rubbery, gritty, and friable. Microscopic examination revealed delicate papillary formations reminiscent of normal choroid plexus, with simple cuboidal to columnar epithelium overlying fibrovascular cores. Light- and electron-microscopic studies demonstrated that the neoplastic cell pigment consisted of both neuromelanin and lipofuscin. To our knowledge, this is the first reported case of neuromelanin pigmentation within a choroid plexus papilloma.     

Cystic tumor in a 4 month old male

Cystic choroid plexus tumor is a rare variant of choroid plexus papilloma (CPP), reported mostly in infants. It is associated with the development of acute hydrocephalus in many cases. The presence of atypical CPP has recently been recognized by the WHO as a grade II tumor with increased mitotic activity. We are reporting a case of a 3.5 month infant who presented with seizures and features of increased intracranial pressure. He was found to have cystic atypical choroid plexus papilloma.     

The fine structure of choroid plexus carcinoma

The ultrastructural findings of two cases of choroid plexus carcinoma occurring in infants 11 and 24 months old are discussed. Both had a similar ultrastructural pattern which demonstrated a clear polygonal cytoplasm, cell polarity towards the lumina, junctional complexes and evidence of a basement membrane, all of which point to an epithelial origin for the proliferating cells. Abundant immature cellular characters such as polyribosomes, glycogen granules and hypertrophied rough endoplasmic reticulum were found. The importance of the differential dignosis from ependymoblastoma and benign choroid plexus papilloma is emphasized. In the former, the major differentiating features are the existence of abundant glial neuropil and cellular characters of glial differentiation, whilst in the latter, cytoplasmic features demonstrate cellular maturity.     

Choroid plexus papilloma in a Scottish highland cow

Choroid plexus papilloma, a rare tumour in bovids, arising from the roof of the third ventricle was diagnosed at necropsy in a 4-year-old Scottish Highland cow. The animal presented with a 2-month history of progressive ataxia, ventromedial strabismus, and hyperaesthesia. Neoplastic epithelial cells were positive immunohistochemically for pancytokeratin and S-100, and negative for GFAP. Ultrastructurally, epithelial cells were characterized by intercellular junctions, zonulae adherens, and zonulae occludens. Neither cilia nor basal bodies were identified. The gross, microscopical, immunohistochemical and ultrastructural findings were consistent with those of a choroid plexus papilloma.     

Choroid plexus papilloma of the fourth ventricle

A 14 year old girl presented with a 6 months' history of headache with vomiting, ataxia and cerebellar signs. CT and MRI revealed obstructive hydrocephalus secondary to a large fourth ventricular mass which enhanced markedly on contrast administration. Histopathology of the resected mass revealed papillary structures lined by cuboidal cells confirming choroid plexus papilloma.     

Renal epithelial neoplasms: the diagnostic implications of electron microscopic study in 55 cases

Several unsettled histogenetic, nosologic and diagnostic considerations for renal epithelial tumors may have ultrastructural ramifications. Yet, a comprehensive electron microscopic study of renal epithelial neoplasms, in light of the recent classification, is not available. The ultrastructural findings from fifty-five renal epithelial neoplasms [31 clear cell renal cell carcinomas (RCC), 11 papillary RCC, 5 chromophobe RCC, 3 sarcomatoid RCC and 5 oncocytomas] were correlated with their light microscopic appearance. Clear cell RCC showed long microvilli similar to the brush border of the normal proximal tubules, with abundant cytoplasmic lipid and glycogen. Papillary RCC showed variably sized microvilli, and small amounts of cytoplasmic lipid, but no glycogen. Chromophobe RCC showed many cytoplasmic vesicles and abnormal mitochondria, with rare short and stubby microvilli. Renal oncocytoma showed many mitochondria with a few vesicles in the apical portion of the cytoplasm and rare short and stubby microvilli. The eosinophilic cell variants of clear cell RCC, papillary RCC and chromophobe RCC showed ultrastructural features similar to those of their respective prototypes, except for an increased numbers of mitochondria in the cytoplasm. One sarcomatoid clear cell RCC showed skeletal muscle differentiation. Two types of cytoplasmic inclusions, i.e. hyaline globules and granules similar to those in the Paneth cells (PC-like granules) were identified only in clear cell RCC, which displayed distinctive ultrastructural features. The current EM study demonstrates distinctive ultrastructural features of renal epithelial neoplasms. The findings lend additional support to the current classification of the pertinent tumor types, facilitate the differential diagnoses, and provide insights into the possible histogenesis of renal epithelial neoplasms.     

Disseminated choroid plexus papilloma. An ultrastructural study

Choroid plexus papilloma is a rare intracerebral neoplasm that occasionally disseminates along the neuraxis. The fine structure of such a metastatic papilloma appears to correspond very closely to that of normal choroid plexus. Lack of capillary endothelial pores is the only meaningful difference. There does not appear to be an ultrastructural feature that is unique to disseminating choroid plexus papilloma.     

Papillary carcinoma of choroid plexus

Summary Two cases of papillary carcinoma, one in a 23-month-old girl and the other in a 25-month-old boy who both died within a relatively short time after operation, were studied histologically and electron microscopically. Both tumors originated in the right trigone of the lateral ventricle and spread widely via the cerebrospinal fluid. Histologically, the tumors consisted mostly of a differentiated papillary architecture closely resembling choroid plexus papilloma. Some carcinoma cells, showing cellular atypism, displayed a multilayer arrangement. The amount and distribution of PAS-, Alcian blue- or orcein-positive substances on the cell surface and/or in the interstitial elements of the carcinomas differed from that of choroid papillomas examined in our laboratory. Electron microscopically, the carcinoma cells in some areas showed a loss of apical-basal polarity, and the formation of both microvilli and desmosome-like structures was indistinct. Papillary carcinoma is reviewed on the basis of the literature from 1906 till 1980.The authors thank Dr. S. Nagayoshi, Dr. N. Hirabayashi and Dr. I. Asamoto, who performed the autopsies, for their permission to publish.     

A 21-year-old female with a third ventricular tumor

A 21-year-old female presented with a 2-months history of tinnitus, vertigo and nausea. On magnetic resonance imaging of the brain, she demonstrated a small contrast-enhancing mass in the posterior part of the third ventricle. Intraoperatively, the tumor showed a close relationship to the choroid plexus of the third ventricle. Histopathology revealed a benign schwannoma of World Health Organization grade I. To our knowledge, only 9 cases of intraventricular Schwann cell tumors have been published so far. Most of these tumors were benign schwannomas, except for 2 cases of malignant peripheral nerve sheath tumors. The tumor of our patient is the first reported schwannoma of the third ventricle. The origin of intraventricular Schwann cell tumors is unknown. They may arise from autonomic perivascular nerves in the choroid plexus or from ectopic neural crest-derived cells. Histologically, intraventricular schwannoma needs to be distinguished from other spindle cell tumors, in particular pilocytic astrocytoma and fibroblastic meningioma.     

内淋巴囊肿瘤2例临床病理特征及误诊原因分析

目的探讨内淋巴囊肿瘤(endolymphatic sac tumor,ELST)的临床及病理形态特点,诊断及鉴别诊断要点,提高对其认识。方法收集2例分别被误诊为脉络丛乳头状瘤及生乳头状汗腺瘤的ELST的临床资料,重新切片行HE染色及免疫组化标记。结果 2例均为男性,以进展性耳聋,外耳道流血或流脓为主要症状。影像学提示颞骨岩部囊实性占位并周围骨质破坏。病理形态特征:肿瘤呈弥漫囊性乳头状结构,乳头表面被覆单层立方或高柱状上皮细胞,轴心为纤维血管组织;部分区域乳头间纤维间质中见腺体结构并囊性扩张,腺腔内可见均质红染的胶样物质。间质纤维组织增生、玻璃样变,见含铁血黄素沉积及胆固醇结晶。免疫组化结果示2例病变肿瘤细胞均表达CK、EMA、CK7、CK19、NSE、CD56和vimentin;其中1例S-100阳性;而GFAP、TTF-1、CEA、TG、Galectin-3、CD10、Syn及CgA均阴性,Ki-67增殖指数低。结论 ELST为罕见的低度恶性肿瘤,临床及病理学特征均易与其他肿瘤混淆。病理组织学形态及免疫组化标记是诊断及鉴别诊断的依据,同时需结合患者特殊发病部位。     

Ependymoma: Ultrastructural Studies of Two Cases

Several unusual ultrastructural findings in two ependymomas are reported. In case 1, a grade I ependymoma of the fourth ventricle, there were rosettes, perivascular pseudorosettes, and tumor cells having unusual intracytoplasmic vacuoles by light microscopy. Ultrastructurally, these vacuoles were frequently microrosettes as well as scattered, degenerated cytoplasmic processes of tumor cells. The lumina of some of the microrosettes were bordered by abnormally long and malformed zonulae adherentiae. In case 2, a recurrent grade III ependymoma of the third ventricle, there were rosettes and perivascular pseudorosettes as well as more cellular and anaplastic areas by light microscopy. Ultrastructurally, the cytoplasmic processes of tumor cells in perivascular pseudorosettes contained frequent dense-core vesicles and occasional parallel arrays of microtubules. These structures do not occur in normal mammalian ependymal cells but do occur in the ependymal tanycyte, a related cell that is plentiful in the walls of the third ventricle. Thus some of the tumor cells of this third ventricle ependymoma appear to have differentiated as tany-cytes.     

Ependymoma: Ultrastructural Studies of Two Cases

Several unusual ultrastructural findings in two ependymomas are reported. In case 1, a grade I ependymoma of the fourth ventricle, there were rosettes, perivascular pseudorosettes, and tumor cells having unusual intracytoplasmic vacuoles by light microscopy. Ultrastructurally, these vacuoles were frequently microrosettes as well as scattered, degenerated cytoplasmic processes of tumor cells. The lumina of some of the microrosettes were bordered by abnormally long and malformed zonulae adherentiae. In case 2, a recurrent grade III ependymoma of the third ventricle, there were rosettes and perivascular pseudorosettes as well as more cellular and anaplastic areas by light microscopy. Ultrastructurally, the cytoplasmic processes of tumor cells in perivascular pseudorosettes contained frequent dense-core vesicles and occasional parallel arrays of microtubules. These structures do not occur in normal mammalian ependymal cells but do occur in the ependymal tanycyte, a related cell that is plentiful in the walls of the third ventricle. Thus some of the tumor cells of this third ventricle ependymoma appear to have differentiated as tany-cytes.     

Signet-ring cell ependymoma: case report with implications for pathogenesis and differential diagnosis

We describe light microscopic, immunohistochemical and ultrastructural features of a signet-ring cell ependymoma (WHO grade II) identified in a surgically resected left cerebellar cystic tumor from a 64-year-old man. Part of the tumor showed clear-cell differentiation. Immunohistochemical coexpression of glial fibrillary acidic protein and epithelial membrane antigen, characteristic of ependymoma, was detected in both components. Sinuous intermediate junctions, cytoplasmic lumina, and scant astroglial filaments were demonstrated by electron microscopy. Signet-ring cell change was shown to be induced by disproportionate cavitation of either microvillus-bearing cytoplasmic lumina or microrosettes. The staining qualities of clear cells were mainly due to paucity and degeneration of subcellular organelles. Therefore, signet-ring cell ependymomas represent a unique anomaly of intra- and extracellular compartmentalization to be distinguished from various unrelated forms of cytoplasmic volume increase, resulting in an optically similar "empty" appearance of tumor cells. As a clinically relevant consequence, signet-ring cell ependymoma must be included in the differential diagnosis of primary or metastatic neoplasms of the central nervous system, having in common a phenotype characterized by overdeveloped optically lucent cell bodies.     

Case of clear cell ependymoma of medulla oblongata: clinicopathological and immunohistochemical study with literature review

Clear cell ependymoma has been included in the WHO classification of the central nervous system in 1993, after the first report by Kawano et al. Since then, only a few cases have been reported. Most clear cell ependymoma cases reported in the literature so far were located in the supra-tentorial compartment and/or cerebellum, and one case was in the cervical spinal cord. We report a case of clear cell ependymoma whose histological features were sufficient for the diagnosis and was unusually located in the fourth ventricle originating from the medulla oblongata. The tumor showed uniform tumor cells with perinuclear halo, nuclei being centrally located. Most of the tumor cells were arranged as perivascular pseudorosettes, and no ependymal canals or rosettes were evident. Mitotic figures were not frequent. Immunohistochemically, the tumor cells were strongly reactive for glial fibrillary acidic protein and vimentin, and weak and dot-like positive for epithelial membrane antigen. Clear cell change of the tumor cells appeared to be fixation artifact because this feature was not evident in the frozen section.     

Ependymoma-like tumor of the mesovarium

We report a case of primary extramedullary ependymoma, arising from the mesovarium in a 47-year-old woman and discovered incidentally during routine hysterectomy for uterine leiomyomas. The tumor exhibited the light microscopic, immunohistochemical, and ultrastructural features of a typical ependymoma, including a prominent pseudorosette pattern, positive staining for glial fibrillary acidic protein, and electron microscopic visualization of microvilli, intermediate filaments, basement membranes, and long cytoplasmic processes. While the occurrence of subcutaneous ependymomas in the sacrococcygeal region and metastatic central nervous system tumors at various sites are familiar, we believe this case to be a rare example of a primary ependymoma arising in a different and unusual extramedullary location.     

Infratentorial giant cell ependymoma: a rare variant of ependymoma

We describe a giant cell ependymoma occurring in a 50-year-old man. The mass was located in the posterior aspect of the foramen magnum, extending from the cerebellar tonsil to the upper cervical spine. The tumor was a highly cellular neoplasm showing biphasic histology. Diffuse sheets of non-cohesive atypical giant cells, having eccentrically located single or multiple nuclei and plump eosinophilic cytoplasm, partly infiltrated the desmoplastic inflammatory stroma. Parts of perivascular pseudorosette-forming or pseudopapillary areas were composed of atypically elongated cells, which looked like conventional anaplastic ependymoma. There was a transitional area between two patterns. Numerous mitoses and focal necrosis were observed. Immunohistochemically, the tumor cells were immunoreactive for glial fibrillary acidic protein, vimentin, S-100 protein, and CD99. None of the tumor cells showed immunoreactivity for epithelial membrane antigen except for the intracytoplasmic lumen of a few vacuolated cells. Ultrastructurally, tumor cells were ependymal in nature; we noted cytoplasmic intermediate filaments and intercellular microrosettes with microvilli, cilia, and long zonula adherens. The features of this tumor, e.g. its superficial location, mixed giant cells, perivascular pseudorosettes or papillaries, complicated its differentiation from rhabdoid/papillary meningioma. However, immunohistochemistry and electron microscopy confirmed the diagnosis of ependymoma. The giant cell variant should be included in the subclassification of the ependymoma.