An immunohistochemical study of papillary tumors in the central nervous system

Pigmented primary epithelial tumor of the sella: A report of an intriguing case

This is a report of an uncommon primary pigmented papillary epithelial tumor of the sella in a 38-year-old man, who presented with clinicoradiological features of pituitary adenoma. Histologically, the tumor showed features reminiscent of choroid plexus papilloma, that is, conspicuous papillary epithelial morphology with presence of intacytoplasmic melanin and no mitotic activity. Immunohistochemically, the tumor was positive for pancytokeratin (AE1/AE3), S-100 protein and CD56, while it was negative for glial fibrillary acid protein, thyroid transcription factor-1, epithelial membrane antigen, other cytokeratins and pituitary hormones. These findings were not typical of any WHO-defined entity and is thus best regarded as a pigmented papillary epithelial tumor of sella of uncertain histogenesis. The present case is a valuable addition to the spectrum of primary pigmented papillary epithelial tumors originating at an unusual location.

Myxopapillary ependymoma with anaplastic features: A case report with review of the literature

Background:

Myxopapillary ependymoma (MPE) with anaplastic features is extremely rare, with only three case reports in the literature.

Case Description:

We report the case of a MPE with anaplastic features in a 24-year-old female who presented with a dominant lumbar mass along with intracranial and sacral metastases. Upon gross total resection of the dominant tumor located at L2-L3, it appeared to arise from the filum terminale, and had a solid component in addition to soft or necrotic areas. Histologically, the tumor was composed of the two classic components of MPE: (1) low-grade ependymal cells surrounding blood vessels, producing the papillary appearance and (2) perivascular myxoid material between blood vessels and ependymal cells, creating the myxopapillary appearance. The high-grade anaplastic component showed hypercellularity, brisk mitotic rate, and vascular proliferation, with frequent pleomorphic cells and atypical mitotic figures. It was positive for vimentin and glial fibrillary acidic protein (GFAP); negative for epithelial membrane antigen (EMA), CAM5.2, creatine kinase 7 (CK7), CK20; and the MIB-1 index (Ki-67) was 8–38%. Ten months after initial resection, follow-up magnetic resonance imaging revealed new lesions in (1) the hypothalamus, (2) the left pons, and (3) the left medial temporal lobe, which were treated with radiosurgery. Eight months later (18 months from initial surgery), the patient underwent thoracic laminectomy for a large leptomeningeal metastasis at T6 and T8.

Conclusion:

The present case of MPE with anaplastic features is the fourth case on record in the medical literature.

Anaplastic myxopapillary ependymoma in an infant: Case report and literature review

A 7-month-old boy presented with gastrointestinal disturbance, mild neurologic deficit of the left lower extremity and levo-scoliosis of the thoracic spine. Magnetic resonance imaging demonstrated a large intramedullary lesion involving the thoracic spine, from level T1 to T11. Histologic analysis showed a glial tumor with fibrillary processes arranged in radial pattern around mucoid fibrovascular cores with a high proliferative index (focally up to 80%) and prominent vascular endothelial hyperplasia. These findings were consistent with an anaplastic myxopapillary ependymoma. Subtotal resection was performed via a T3-T10 laminoplasty. A ventricular shunt was placed, and the patient subsequently received chemoradiation therapy. To date, this is the second case of a myxopapillary ependymoma with high-grade anaplastic features and the first case in an infant reported in the literature.

An unusual location for a choroid plexus papilloma: the pineal region

PURPOSE

Choroid plexus papillomas (CPP) are rare benign neoplasms of the central nervous system that occur most often in children during the first decade of life. They occur most often in the lateral ventricle. It is extremely rare for a CPP to occur in the pineal region. We describe the case of a child with a CPP located in the pineal region, who was initially diagnosed with obstructive hydrocephalus by cranial computed tomography (CT).

METHODS

A 9-year-old female patient presented with complaints of visual disturbance, nausea, and vomiting. Magnetic resonance imaging (MRI) showed a poor contrast-enhanced pineal-localized lesion. Anatomical variations within the patient caused her surgery to proceed using a supratentorial-occipital interhemispheric approach.

RESULTS

The tumor was totally removed, and a histological examination revealed the tumor to be a typical CPP. The patient received follow-up neurological and ophthalmologic examinations at 3, 6, 9, 12, 24, and 36 months postoperatively, which demonstrated her progressive improvement.

CONCLUSIONS

CPPs may have a wide range of locations and resulting symptoms. However, the pineal region is a rarely encountered location, particularly for pediatric patients. It is of great value to correctly differentiate neoplasms such as germ cell tumors, pineocytomas, meningiomas, and astrocytomas, so that patients receive the correct diagnosis and treatment approach.

Choroid plexus papillomas: advances in molecular biology and understanding of tumorigenesis

Choroid plexus papillomas are rare, benign tumors originating from the choroid plexus. Although generally found within the ventricular system, they can arise ectopically in the brain parenchyma or disseminate throughout the neuraxis. We sought to review recent advances in our understanding of the molecular biology and oncogenic pathways associated with this disease. A comprehensive PubMed literature review was conducted to identify manuscripts discussing the clinical, molecular, and genetic features of choroid plexus papillomas. Articles concerning diagnosis, treatment, and long-term patient outcomes were also reviewed. The introduction of atypical choroid plexus papilloma as a distinct entity has increased the need for accurate histopathologic diagnosis. Advances in immunohistochemical staining have improved our ability to differentiate choroid plexus papillomas from other intracranial tumors or metastatic lesions using combinations of key markers and mitotic indices. Recent findings have implicated Notch3 signaling, the transcription factor TWIST1, platelet-derived growth factor receptor, and the tumor necrosis factor-related apoptosis-inducing ligand pathway in choroid plexus papilloma tumorigenesis. A combination of commonly occurring chromosomal duplications and deletions has also been identified. Surgical resection remains the standard of care, although chemotherapy and radiotherapy may be considered for recurrent or metastatic lesions. While generally considered benign, these tumors possess a complex biology that sheds insight into other choroid plexus tumors, particularly malignant choroid plexus carcinomas. Improving our understanding of the molecular biology, genetics, and oncogenic pathways associated with this tumor will allow for the development of targeted therapies and improved outcomes for patients with this disease.

A pediatric intramedullary spinal cord tumor with unusual solid-cystic and papillary features: a case report

Spinal cord tumors are rare in children. We report a novel case of pediatric intramedullary spinal cord tumor with unusual solid-cystic and papillary features. Clinically, the patient presented at the age of 3 years with motor deficit and urinary incontinence, and MRI demonstrated multilocular cystic lesions in the thoracic spine. Histologically the tumor consisted of solid, sheet-like components and branching papillary structures, and immunohistochemistry demonstrated positive reactivity for epithelial membrane antigen, cytokeratins (7, AE1/3, CAM5.2), E-cadherin and transthyretin, and negativity for GFAP, S-100 protein, synaptophysin and neurofilament. These histological and immunohistochemical findings appeared to be unique, and were not compatible with the features of classical ependymoma or choroid plexus papilloma. The clinical behavior, characterized by relatively rapid tumor regrowth after surgical resection and a relatively high MIB-1 labeling index, suggest that this tumor might have had moderate malignant potential. This pediatric case appears to be particularly informative with regard to the tumor biology or tumorigenesis of intramedullary spinal cord tumor with unusual solid-cystic and papillary features.

Anaplastic astroblastoma: a rare glial tumour

Astroblastoma is a rarely diagnosed primary brain neoplasm whose histogenesis has been clarified recently. It occurs in children and young adults and presents as a well-circumscribed, contrast enhancing lesion in the cerebral hemisphere. Here the authors present a case of 25-year-old woman with an astroblastoma in the left frontal convexity that was excised. The characteristic radiological and histopathological features of this case are described. An astroblastoma should be included in the differential of a localised brain tumour, especially in a young patient.

Primary choroid plexus papilloma in the pituitary fossa: case report and literature review

Choroid plexus papillomas are rare tumors of the central nervous system and are usually confined to the ventricular system. We illustrated a primary choroid plexus papilloma in the pituitary fossa. A 31-year-old female presented with amenorrhea and intermittent galactorrhoea, with no visual complaints in the last 2 years. Endocrine testing showed no hormone excess or deficiency of the pituitary and target glands, except for a higher prolactin level (56 ng/ml). A sharply circumscribed regular mass in the sellar region occupying the entire sella turcica and extending into the suprasellar cistern was demonstrated on MR imaging with gadolinium diethylenetriamine pentaacetic acid. The patient underwent an endonasal trans-sphenoidal approach. Complete microsurgical excision and complete preservation of the normal pituitary gland was achieved, with normal prolactin level. The histopathology showed that the lesion was a choroid plexus papilloma. Theories of the origin, the differential diagnosis, and treatment of the rare tumor are discussed.

Increased incidence of choroid plexus carcinoma due to the germline TP53 R337H mutation in southern Brazil

Background

Choroid plexus carcinomas (CPC) are rare tumors predominantly found in children. Given the high frequency of the germline R337H mutation in the TP53 gene in southern Brazil, we have evaluated the frequency of the R337H mutation in families with CPC in children.

Methodology/Principal Findings

The present series included 29 patients that were admitted to the same institution from 1992 to 2010, including 22 children with CPC (0.08–13.6 years of age at diagnosis) and 7 children with papilloma of the choroid plexus (Pp; 0.5–9.8 years of age). Surgical resection was possible in 28 children. Blood and/or tumor DNA was extracted and analyzed using PCR-RFLP and results were confirmed by sequencing 240 bp of the TP53 exon 10. The patients, all parents, and some relatives submitted samples for blood DNA analysis. In addition, we have also examined the presence of the mutation in DNA from paraffin-embedded tumor samples to evaluate loss of heterozygosity. We found 63.3% (14/22) of the CPC patients positive for the germline R337H mutation; CPC samples were either heterozygous (n = 7), lost only the wild-type (n = 4), or only the R337H copy (n = 2). One CPC sample was not available. All Pp cases (7/7, 100%) were negative for R337H. Cure (>5 years survival free of disease) was observed in 18.1% of the CPC cases with the R337H mutation (2/11), 71.4% of the Pp (5/7), and 25% of CPC cases negative for the R337H mutation (2/8). Family history of cancer (with 2 or more cancer cases) was exclusively identified on the parental side segregating the R337H mutation, and 50% (7/14) of them were compatible with Li-Fraumeni-like syndrome.

Significance

Our results show for the first time that the R337H TP53 mutation is responsible for 63% of the CPC cases in children, suggesting a higher incidence of CPC in southern Brazil.

Pineal parenchymal tumor of intermediate differentiation with papillary features: a continuum of primary pineal tumors?

Pineal parenchymal tumors comprise a rare group of primary neoplasms of the pineal gland. We describe a case involving a 29-year-old woman who presented with signs and symptoms of hydrocephalus secondary to a pineal region tumor obstructing the third ventricle. Surgical resection was performed and pathological analysis revealed a novel diagnosis consistent with a pineal parenchymal tumor of intermediate differentiation (PPTID) with transition to a papillary tumor of the pineal region (PTPR). To our knowledge, this particular pineal region tumor pathology has not yet been reported in the literature and highlights the continuum with which primary pineal tumors exist. We provide a review of the existing literature on pineal region tumors, specifically PTPR and PPTID, and offer insight into the management of these rare neoplasms.

Papillary Tumor of the Pineal Region of a Dog

A 3-year-old, intact, male Beagle dog developed clinical signs of pleurothotonus and altered head position to the right, neck pain, nystagmus, hyperreflexia of the left forelimb, and hyperextension of both forelimbs. Magnetic resonance imaging enabled a tentative diagnosis of thalamic neoplasia with incidental hydromyelia at the level of the second cervical vertebra. The animal was euthanatized due to the poor prognosis, and a necropsy was performed. A large, well-demarcated, nonencapsulated, and focally infiltrative mass was present in the approximate location of, and effacing, the pineal gland. The mass was composed of densely packed polyhedral neoplastic cells that exhibited epithelial characteristics, such as intercellular junctions, and contained carbohydrate granules and occasionally melanin granules. Immunohistology confirmed that neoplastic cells expressed neuron-specific enolase and, in a small proportion, cytokeratin. These combined findings led to the diagnosis of a papillary tumor of the pineal region, a tumor not previously described in dogs.

Ependymal tumors

Ependymomas represent a heterogeneous group of glial tumors whose biological behavior depends on various histological, molecular, and clinical variables. The scope of this chapter is to review the clinical and histo-logical features as well as the molecular genetics of ependymomas with special emphasis on their influence on tumor recurrence and prognosis. Furthermore, potential molecular targets for therapy are outlined.

Cytokeratin positivity in myxopapillary ependymoma--a potential diagnostic pitfall

Background

Myxopapillary ependymomas (MPE) occur in the filum terminale of the spinal cord, but also present in extra-spinal locations such as subcutaneous tissue and brain. They are slow growing grade I gliomas. Areas of solid growth pattern with aggregates of cells with "epithelioid morphology" seen in MPE can mimic metastatic carcinoma. The presence of occasional cells with clear cytoplasm and morphology can resemble Chordoma. Diagnosis can be missed due to these morphological similarities, which could affect patient management and hence, long term survival.

Case presentation

We describe two cases of MPE with cytokeratin (AE1 AE3, CAM 5.2, Cytokeratin 7 and cytokeratin 20) expression.

Conclusion

MPE can be positive for Cytokeratins (CAM 5.2, AE1 AE3, CK7) and focally for EMA, which could be misdiagnosed as metastatic carcinoma. In cases demonstrating epithelioid and clear cell morphology, the diagnosis of MPE should be made in conjunction with histology, proper immunohistochemical profile which includes co-expression of GFAP, S-100 protein and epithelial markers, radiologic findings and site. It is important to be aware of the cytokeratin profile in MPE to avoid erroneous diagnosis with other tumour entities.

Hypothalamic papillary tumor in a patient with tuberous sclerosis

We here report an unusual tumor of the suprasellar region featuring a papillary growth pattern and cytokeratin expression in a 10-year-old boy with tuberous sclerosis. This hitherto undescribed low-grade hypothalamic tumor extends the spectrum of tumors associated with the tuberous sclerosis complex.

MR imaging of papillary tumor of the pineal region

We report the imaging features of 4 cases of patients with papillary tumor of the pineal region, a tumor newly recognized in the 2007 World Health Organization "Classification of Tumors of the Nervous System." In each case, the tumor was intrinsically hyperintense on T1-weighted images with a characteristic location in the posterior commissure or pineal region. The pathologic hallmarks of the tumor are discussed, including a possible explanation for the MR imaging characteristics in our cases.

Papillary Tumors of the Pineal Region: Case Report

OBJECTIVE

The pineal region is a rare intracranial site for metastasis. We report three patients initially considered to have metastatic papillary adenocarcinoma to the pineal region. On review, these papillary, keratin-positive neoplasms meet the criteria for papillary tumor of the pineal region (PTPR).

CLINICAL PRESENTATION

These neoplasms occurred in three women (age range, 37–55 yr). Imaging studies demonstrated well-circumscribed lesions in the pineal region. All patients presented with obstructive hydrocephalus and symptoms attributable to hydrocephalus and tectal compression.

INTERVENTION

All three patients underwent near total microsurgical resection of the pineal region neoplasm, followed by adjuvant radiotherapy. The two patients with long-term follow-up (56–60 mo) have remained clinically stable without evidence of local or distant recurrence. The first two patients were initially diagnosed as having papillary metastatic carcinoma of unknown origin. The third patient was treated after the recent description of PTPR and met the histopathological diagnostic criteria. Retrospective pathological review of the previous two patients resulted in designation as PTPR.

CONCLUSION

The morphological features of the tumors in our series, along with the clinical presentations, are similar to those in the original description of the PTPR. Our findings agree with the original hypothesis that the cells composing the PTPR are similar to ependymal cells of the subcommissural organ, thus furthering the hypothesis that the PTPR derives from a specialized ependymocyte associated with the subcommissural organ. The two patients with long-term follow-up (56–60 mo) have remained clinically stable without evidence of local or distant recurrence.

Choroid plexus carcinoma secreting carbohydrate antigen 19-9 in an adult. Case report

A 53-year-old man presented with a choroid plexus carcinoma in the body of the right lateral ventricle manifesting as gait disturbance due to left mild hemiparesis and papilledema. Subtotal removal of the tumor was performed. Histological examination revealed well-differentiated papillary adenocarcinoma. Immunohistochemical examination showed intense reactivity for carbohydrate antigen 19-9 (CA19-9). The serum level of CA19-9 was significantly high, but decreased rapidly after radiation therapy. Systemic examinations found no malignancy in other organs. This second case of choroid plexus carcinoma producing CA19-9 indicates that CA19-9 may be a useful marker of choroid plexus carcinoma.

Choroid plexus adenoma: case report and review of the literature

CASE REPORT

An 8-month-old infant with macrocephaly was found to have hydrocephalus and a cystic third ventricular tumour; biopsy of the tumour showed a choroid plexus adenoma. The tumour was attached to the ependymal lining and was strongly adherent to the walls and floor of the anterior third ventricle.

TREATMENT

After biopsy, it was felt that a radical resection would carry a high risk of injury to the floor of the third ventricle and cause new neurological deficits. Therefore, an external ventricular drain was inserted and bilateral ventriculo-peritoneal shunts were inserted 1 week post-operatively. In view of the benign nature of the tumour, no adjuvant radiotherapy or chemotherapy was given.

OUTCOME

There was no further tumour growth or clinical deterioration over a 6-year follow-up period.

INI1 Protein Expression Distinguishes Atypical Teratoid/Rhabdoid Tumor from Choroid Plexus Carcinoma

Central nervous system atypical teratoid/rhabdoid tumor (AT/RT) and choroid plexus carcinoma (CPC) are rare, highly malignant tumors that predominantly arise in infants and young children. Overlapping clinical, histologic, ultrastructural, or immunophenotypic features may obscure the diagnosis in some cases. AT/RT is characterized by deletions and/or mutations of the INI1 tumor-suppressor gene on chromosome band 22q11.2. We have recently developed an INI1 immunohistochemical staining assay. Negative staining of tumor cells resulting from inactivation of the INI1 gene is a consistent feature of AT/RT. Mutations of INI1 in some CPCs have been reported. The purpose of the present study was to determine if immunohistochemical staining with an INI1 antibody would provide a sensitive means of distinguishing between CPC and AT/RT. We examined 28 tumors with a submitted diagnosis of CPC. Twenty-one CPCs showed retained expression of INI1 and seven tumors showed loss of INI1 expression. Cytogenetic, FISH, and/or INI1 mutation results were also available for 13 tumors. In three of the seven cases, monosomy 22 was the only cytogenetic abnormality, suggestive of AT/RT. However, monosomy 22 was also identified in 3 tumors with complex karyotypes that retained INI1 expression. The 7 tumors that were immunonegative for INI1 had features that were consistent with AT/RT. Immunostaining for INI1 protein is retained in the majority of CPC and is lost in AT/RT. This expression pattern seems to better define the 2 groups of tumors than does light or electron microscopy, routine immunohistochemistry, or cytogenetic analysis alone.

Expression of cytokeratin by malignant meningiomas: diagnostic pitfall of cytokeratin to separate malignant meningiomas from metastatic carcinoma

Based on clinical and histologic features, differentiating metastatic carcinomas from benign or malignant meningiomas usually is not difficult. Occasionally, however, in some patients without a clinical history of carcinoma, malignant meningiomas can morphologically simulate metastatic carcinoma, necessitating an immunohistochemical study for cytokeratin to make a correct diagnosis. However, the utility of immunohistochemical markers to separate malignant meningioma from metastatic carcinoma has not been investigated. The immunoperoxidase method with antigen retrieval was used to characterize the expression of three cytokeratins (AE1/AE3, CAM 5.2, and Pan cytokeratin), EMA, CEA, Ber-EP4, CD 15, and B72.3 in 12 previously diagnosed malignant meningiomas, 20 benign meningiomas, and 20 metastatic carcinomas. Cytokeratin expression was detected in 75% of malignant meningiomas, 0% of benign meningiomas, and 100% of metastatic carcinomas. While epithelial markers of Ber-EP4, CEA, B72.3 and CD-15 were positive in 90, 80, 70 and 65% of the metastatic carcinoma, respectively, they were negative in all 12 malignant meningioma examined. Vimentin immunoreactivity was seen in all benign and malignant meningiomas, and in 20% of metastatic carcinomas. Our results indicated that cytokeratin is not a reliable immunohistochemical marker to separate a malignant meningioma from metastatic carcinoma. A panel of epithelial markers including Ber-EP4, CEA, B72.3 and CD-15, and vimentin may be needed to separate malignant meningioma from metastatic carcinoma. Cytokeratin expression can be a potential pitfall for confusing a malignant meningioma with a metastatic carcinoma.

Myxopapillary ependymoma with anaplastic features

A case of myxopapillary ependymoma with anaplastic features in 15-year-old boy is reported. The tumor was located in the intradural space extending to the 12th thoracic to 2nd lumbar vertebral level. It was excised with the accompanying spinal arch of the T12 to L2 vertebra. At operation, the tumor was not attached to the surrounding soft and bony tissues. The tumor, measuring 49 x 19 x 15 mm, was brownish-yellow in color and involved the conus medullaris and filum terminale. Histologically, the tumor was composed of biphasic features of a hypercellular papillary growth area and a hypocellular myxoid area. In the papillary growth area, ependymal rosettes and perivascular pseudorosettes were observed. These findings were consistent with those of a myxopapillary ependymoma, although multiple foci of punctate necrosis within the tumor and proliferation of endothelial cells showing glomeruloid structures were observed. Many mitotic figures were also observed. In addition, the Ki-67 labeling index of tumor cells was 10.1%. These findings are unusual for myxopapillary ependymoma, and therefore, it appeared that the diagnosis of myxopapillary ependymoma with anaplastic features was appropriate.

Papillary tumor of the pineal region

Primary papillary tumors of the central nervous system are rare. We have encountered a series of six papillary tumors of the pineal region with distinctive features that appear to represent a clinicopathologic entity. The tumors occurred in four women and two men, ranging in age from 19 to 53 years. Imaging studies showed a large well-circumscribed mass in the pineal region. The tumors were characterized by an epithelial-like growth pattern, in which the vessels were covered by a layer of tumoral cells. In papillary areas, the neoplastic cells were large, columnar or cuboidal, with a clear cytoplasm. Nuclei, round or infolded, were found generally at the basal pole of tumoral cells. Immunohistochemically, the tumor cells showed strong staining for cytokeratin, S-100 protein, neuron-specific enolase, and vimentin but only weak or no staining for epithelial membrane antigen and glial fibrillary acid protein. Ultrastructural examination of two cases revealed abundant rough endoplasmic reticulum with distended cisternae filled with secretory product, microvilli, and perinuclear intermediate filaments. The morphofunctional features of these papillary tumors of the pineal region, remarkably uniform within this series, are similar to those described for ependymal cells of the subcommissural organ, and the papillary tumors of the pineal region may be derived from these specialized ependymocytes.

Epithelial differentiation and proliferative potential in spinal ependymomas

The aim of this investigation was recognition of the epithelial differentiation and proliferative activity of ependymomas in the spinal cord compared with astrocytomas in the spinal cord and ependymoma in the brain. We investigated histopathological and immunohistochemical examination in thirty-five cases, including eleven ependymomas, thirteen astrocytomas in the spinal region and eleven ependymomas in the intracranial region. An anti-epithelial membrane antigen antibody (EMA), and two types of anti-cytokeratin antibodies, CAM 5.2 (45 and 52 kDa) and keratin (56 and 64 kDa) were applied as epithelial markers. The proliferative potential of the tumors was investigated using the Ki-67 labeling index (LI, %). Histologically, perivascular pseudorosettes were seen in all of the spinal and intracranial ependymomas. There were few ependymal structures in the spinal ependymomas except in the myxopapillary type. Immunohistochemical study demonstrated that nine (82%) were immunoreactive for EMA, eight (73%) were immunoreactive for CAM 5.2 and three (27%) were immunoreactive for keratin in the spinal ependymomas. In the spinal astrocytomas, no tumors were immunoreactive for EMA or CAM 5.2. One of thirteen cases was immunoreactive for keratin. The Ki-67 LI of the spinal ependymomas was lower than that of the intracranial ependymoma (p < 0.01). Epithelial differentiation was found in the ependymomas which may reflect the differences in histological and biological features between ependymomas and astrocytomas in the spinal cord. Regional differences in ependymomas may influence not only clinical features but also histo-pathological characteristics.

Schneiderian papillomas and nonsalivary glandular neoplasms of the head and neck

Schneiderian papillomas and nonsalivary glandular neoplasms of the head and neck continue to be a source of confusion for both the clinician and pathologist. An update on these lesions is provided.

Choroid plexus papilloma diagnosed by crush cytology

In a 32-yr-old man, an infratentorial cystic lesion with a mural nodule was interpreted to be either a hemangioblastoma or a cystic astrocytoma on CT scan. Intraoperative crush cytology revealed it to be a choroid plexus papilloma (CPP). The utility of crush cytology in the rapid diagnosis of central nervous system (CNS) tumors and the differential diagnosis of CNS papillary lesions are highlighted in this report.

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%.

Cytokeratin 7 and 20 expression in choroid plexus tumors: utility in differentiating these neoplasms from metastatic carcinomas

Tumors derived from choroid plexus epithelium are uncommon and may exhibit a wide variety of histologic patterns. They often are difficult to distinguish from metastatic carcinomas. Previous studies that addressed this issue yielded conflicting results. Recent reports have demonstrated that evaluation of coordinate expression of cytokeratin (CK) 7 and CK20 aids in distinguishing primary from metastatic lesions in a number of anatomic sites and that tumors that commonly are metastatic to the brain retain their CK7/CK20 immunophenotype in this location. We examined 35 choroid plexus tumors with a panel of antibodies to determine their CK7/CK20 immunophenotype. Tumors from 35 patients (7 male, 28 female; mean age, 25 years), including 31 choroid plexus papillomas and 4 atypical papillomas, were evaluated. All tumors were intraventricular or within the cerebellopontine angle and composed predominantly of orderly columnar epithelial cells resting on distinct fibrovascular cores. Atypical papillomas contained combinations of focal loss of architectural pattern, increased mitotic activity, necrosis, and brain parenchymal invasion. No lesion was unequivocally malignant. Twenty-six tumors (74%), including all atypical papillomas, were CK7 positive and CK20 negative. Two tumors stained with both markers, one stained with CK20 only, and six stained with neither marker. Other findings included expression of glial fibrillary acidic protein in 24 tumors, S-100 protein in 19 tumors, transthyretin in 31 tumors, Ber EP4 in 1 tumor, CAM5.2 in 33 tumors, epithelial membrane antigen in 4 tumors, and pancytokeratin in 27 tumors. Our results indicate that the majority of choroid plexus tumors have a CK7-positive/CK20-negative immunophenotype. This finding may be useful in differentiating these lesions from metastatic carcinomas that have differing CK7/CK20 profiles.

[Choroid plexus carcinoma: report of 15 cases]

Choroid plexus carcinoma (CPC) are rare central nervous system tumours derived from choroid plexus epithelium, affecting mainly children under 3 years of age. We present a clinical, epidemiological and histopathological study of 15 cases of CPC. Ten patients were male. Age ranged from 4 months to 21 years (mean=3,4). The lateral ventricles were affected in 73,3% of cases. Main symptom were: hydrocephalus (62.5%), intracranial hypertension (25%) and convulsion (12.5%). The patients were treated by surgery with partial resection in 75% of cases and total resection in 25%. There was one death due to surgical complication, 85.7% of patients had recurrence of tumours with mean survival rate of 13.6% months after diagnosis. Only one patient remain alive 5 years after initial treatment. These results support the poor prognosis and high mortality rate of CPC.

The immunophenotype of ependymomas

The morphologic distinction of ependymomas with epithelial cytology from metastatic carcinoma may pose a significant problem in differential diagnosis. The known presence of keratin in glioma cells further complicates the issue. Using the labeled streptavidin-biotin method with automated staining, we studied epithelial and glial marker expression in 52 ependymomas of varying type and grade, including 20 epithelial-appearing, 14 glial-appearing, eight mixed pattern, and 10 myxopapillary tumors; 38 were low grade and 14 anaplastic. All tumors were immunoreactive for glial fibrillary acidic protein (GFAP), and S-100 protein. Diffuse staining for GFAP was noted in glial-appearing ependymomas featuring perivascular pseudorosettes. Diffuse immunostaining for S-100 protein was seen in cellular lesions exhibiting epithelial-like features. Staining was more diffuse for GFAP than S-100 protein in anaplastic ependymomas. Keratin (AE1/AE3) reactivity was seen in 98% of cases, the pattern being similar to that of GFAP. The frequency of staining for other keratins varied: wide-spectrum keratin (35%), cytokeratin (CK)7 (20%), CAM 5.2 (19%), CK903 (14%), and CK20 (8%); as a rule, it was scant and limited to occasional cells and processes. epithelial membrane antigen (EMA) staining was seen in 36% of all cases and in 67% of epithelial-appearing tumors wherein it often high-lighted microlumina. Aside from AE1/AE3 staining and very infrequent wide-spectrum keratin and EMA reactivity, expression of epithelial markers was not seen in anaplastic ependymomas. No carcinoembryonic antigen (CEA) positivity was noted in any case. Collagen IV reactivity was limited to tumor cell-stroma interfaces. Although variable, S-100 protein and GFAP staining is seen in all ependymomas, particularly in true and perivascular pseudorosettes. Widespread reactivity for keratin AE1/AE3 corresponds closely to the pattern of GFAP staining. Significant staining for other keratins or for CEA is inconsistent with a diagnosis of ependymoma. EMA reactivity is largely limited to luminal staining of rosettes and tubules.

Pathology of choroid plexus papillomas: a review

Choroid plexus papillomas (CPPs) are rare, usually slow growing neoplasms. Their biological behaviour cannot be predicted in an individual case. Furthermore, the neuropathological diagnosis of these neoplasms is occasionally difficult because light and electron microscopical and immunohistochemical features may overlap with those of other neoplasms localising in the choroid plexus. The aim of this paper is to review the pathological literature (light and electron microscopy (EM) and immunocytochemistry), to provide guidance on current diagnostic tools and criteria and address the identification of 'atypical' CPPs, e.g. those CPPs with histological features indicative of aggressive behaviour, in an attempt to help bridge the diagnostic gap between benign CPPs on the one hand and choroid plexus carcinomas (CPCs) on the other.

Transthyretin expression in medulloblastomas and medulloblastoma cell lines

Transthyretin is a protein crucial to the transport of lipophilic molecules such as thyroid hormones and retinoids. In the central nervous system, large amounts of transthyretin are synthesized by the choroid plexus and are secreted into the cerebrospinal fluid. The choroid plexus is the only site of transthyretin synthesis in the brain. Transthyretin is expressed by most benign and malignant choroid plexus tumours while gliomas and meningiomas do not express transthyretin. Other major sites of transthyretin synthesis are the retinal pigment epithelium and hepatocytes. Medulloblastoma is the prototypical primitive neuroectodermal tumour of the cerebellum and can show multiple lines of differentiation, including the expression of retinal markers. In this study, we examined transthyretin expression both at the RNA and protein level in four medulloblastomas and six medulloblastoma cell lines using Northern and Western blot analysis, reverse transcription polymerase chain reaction (PCR), RNA in situ hybridization, and immunohistochemistry. All four medulloblastomas and five of the six medulloblastoma cell lines expressed transthyretin-mRNA as demonstrated by reverse PCR and in situ hybridization while three medulloblastomas and one cell line were positive on Northern blot. The medulloblastoma with the most abundant RNA expression was transthyretin-immunoreactive on cryosections and the medulloblastoma cell line that was positive on Northern blot also expressed transthyretin at levels detectable by Western blot. No transthyretin-immunoreactivity was seen in 16 additional medulloblastomas studied on paraffin sections. These findings indicate that low-level expression of transthyretin-mRNA is common in medulloblastomas and medulloblastoma cell lines. Expression of transthyretin protein occurs rarely but can reach significant levels. Transthyretin expression in medulloblastoma is consistent with retinal pigment epithelium differentiation in medulloblastomas and reflects their pluripotential nature. Furthermore, the potential for transthyretin-immunoreactivity in medulloblastoma should be kept in mind when performing immunohistochemical studies on poorly differentiated cerebellar tumours.

Differential expression of cell adhesion molecules (CAM), neural CAM and epithelial cadherin in ependymomas and choroid plexus tumors

A series of frozen specimens of 18 ependymomas and 7 choroid plexus tumors were examined for their expression of cell adhesion molecules, such as neural cell adhesion molecule (NCAM), its polysialylated isoforms (PSA NCAM), and epithelial (E-) cadherin, and of intermediate filament proteins, such as glial fibrillary acidic protein (GFAP) and cytokeratin, using various monoclonal and polyclonal antibodies. Normal choroid plexus and ependyma were taken as controls. Anti-E-cadherin immunoreactivity was observed on the basolateral part of most adult choroid plexus and benign choroid plexus papilloma cells. However, a small number of atypical papillomas and carcinoma cells showed anti- E-cadherin immunoreactivity throughout their cell surface membrane. NCAM were not expressed by adult choroid plexus and benign papilloma cells. Only a few cells expressed NCAM and PSA NCAM in developing choroid plexus, atypical papillomas and carcinomas. Cytokeratin expression was always observed in choroid plexus and their tumors; GFAP expression was variable from case to case. In contrast, ependymal cells and their tumors never expressed E-cadherin but strongly expressed NCAM. PSA NCAM was found in ependymomas exhibiting anaplastic features. All ependymomas strongly expressed GFAP and a few demonstrated slight expression of cytokeratin. These data suggest that, besides GFAP and cytokeratin, NCAM and E-cadherin are of potential diagnostic value in distinguishing choroid plexus tumors from ependymomas. E-cadherin and NCAM may play a role in the functional organization of normal choroid plexus and ependyma, respectively. In particular, incomplete or irregular anti-E-cadherin expression in choroid plexus tumors and PSA NCAM immunoreativity in ependymomas and choroid plexus tumors correlates with the emergence of anaplastic histological features.

A polymerase-chain-reaction assay for the specific identification of transcripts encoded by individual carcinoembryonic antigen (CEA)-gene-family members

Carcinoembryonic antigen (CEA) is a tumor marker that belongs to a family of closely related molecules with variable expression patterns. We have developed sets of oligonucleotide primers for the specific amplification of transcripts from individual CEA-family members using the reverse transcriptase/polymerase chain reaction (RT/PCR). Specific primer sets were designed for CEA, non-specific cross-reacting antigen (NCA), biliary glycoprotein (BGP), carcinoembryonic antigen gene-family members 1, 6 and 7 (CGM1, CGM6 and CGM7), and one set for all pregnancy-specific glycoprotein (PSG) transcripts. Primers were first tested for their specificity against individual cDNA clones and product-hybridization with internal, transcript-specific oligonucleotides. Total RNA from 12 brain and 63 gynecological tumors were then tested for expression of CEA-related transcripts. None were found in tumors located in the brain, including various mesenchymal and neuro-epithelial tumors. CEA and NCA transcripts were, however, present in an adenocarcinoma located in the nasal sinuses. In ovarian mucinous adenocarcinomas, we always found co-expression of CEA and NCA transcripts, and occasionally BGP mRNA. CEA-related transcripts were also found in some serous, endometrioid and clear-cell ovarian carcinomas. CEA, NCA and BGP transcripts were present in endometrial carcinomas of the uterus and cervical carcinomas, whereas uterine leiomyomas were completely negative. No transcripts were found from CGM1, CGM6, CGM7 or from PSG genes in any of the tumors tested. The PCR data were compared with immunohistochemical investigations of ovarian tumors at the protein level using CEA (26/3/13)-, NCA-50/90 (9A6FR) and NCA-95 (80H3)-specific monoclonal antibodies.

The use of immunomorphology to differentiate choroid plexus tumors from metastatic carcinomas

BACKGROUND

The histologic and immunohistologic differential diagnosis of choroid plexus papillomas/plexus carcinomas (PP/PC) versus metastatic carcinoma in the brain is problematic.

METHODS

Thirty-four choroid PP/PC from 28 patients, 5 normal choroid plexus, and 45 cerebral metastatic carcinomas were immunohistochemically examined with the monoclonal anti-epithelial noncytokeratin antibodies HEA 125 and Ber EP4 using the alkaline phosphatase anti-alkaline phosphatase (APAAP) method.

RESULTS

Normal choroid plexus epithelium was consistently negative. Sections from PP/PC of 3 of 28 patients demonstrated immunoreactivity for these antibodies. In contrast, 43 of 45 cerebral metastatic carcinomas displayed positive immunostaining for HEA 125, and 44 of these 45 carcinomas were positive for Ber EP4. Thus, sensitivity was higher for these antibodies than for the monoclonal anticytokeratin antibody KL1 (41/45). All three HEA 125/Ber EP4-positive PP/PC contained periodic acid-Schiff (PAS)-positive, tall columnar tumor cells. The intensively HEA 125, Ber EP4, and PAS-positive PP/PC were interpreted as possible transitional forms of the mucus-secreting and acinar PP/PC:

CONCLUSIONS

Despite this restriction, the authors proposed the application of HEA 125 and Ber EP4 as a reliable tool in the differential diagnosis of PP/PC versus metastatic carcinoma, especially in combination with glial fibrillary acid protein and transthyretin. Currently, all HEA 125/Ber EP4-positive PP/PC in patients older than 20 years proved to be metastatic carcinomas during their clinical course.

Astroblastoma: report of a case with ultrastructural, cell kinetic, and cytogenetic analysis

Astroblastomas are rare tumors of cerebral hemispheres of young adults. We report an astroblastoma in a 15-year-old girl and present the first descriptions of cytogenetic abnormalities in this tumor. The tumor was relatively well demarcated from the brain and revealed prominent perivascular rosettes as well as intervascular clear cells that contained abundant glycogen. Cytogenetic analysis revealed an abnormal hypodiploid karyotype with 45 chromosomes and monosomies of chromosomes 10, 21, and 22 and two marker chromosomes in all cells examined. The tumor had a Ki-67 labelling index of 4.7% and assessment of ploidy by flow cytometry revealed 96% of cells in the G0G1 phase and 4% of cells in the G2M phase. Assessment of proliferation and ploidy indices in further cases may provide important prognostic data for this poorly understood entity. Further cytogenetic studies will also help to identify if there are consistent karyotypic abnormalities in these enigmatic tumors.

Carcinoma of the choroid plexus: a pediatric experience

Carcinoma of the choroid plexus (CCP) is a rare tumor of the central nervous system which occurs more frequently in patients under 3 years of age. We report 10 cases of CCP in children. There were 5 males and 5 females, aged 5 to 84 months at diagnosis (median 32 months). Eight CCP were located in the lateral ventricle and 2 in the fourth ventricle. All patients underwent initial surgery, with complete resection in 5 cases. Postoperative treatment included radiotherapy alone in 4 patients, chemotherapy alone in 4, both in 1 patient, and no further treatment in one patient. Six patients remain in first continuous complete remission with a follow-up of 12 to 156 months (mean 34 months). Five of these six patients had a complete surgical resection of their tumor and 4 of them received chemotherapy alone. A comparison with the series in the literature suggests that total resection of the tumors is the major prognostic factor for survival. Recourse to additional treatments to prevent local relapses and CNS dissemination seems necessary. In our opinion, radiotherapy should be avoided as far as possible because of its deleterious effect in very young children. As some of the long term survivors did not receive radiation treatment, we conclude that CCP can be treated post operatively using chemotherapy protocols designed for infants with malignant brain tumors.

Immunolocalization of prealbumin (transthyretin) in renal cell carcinoma

Fourteen primary and nine metastatic renal cell carcinomas were examined with a commercially available antibody against prealbumin (transthyretin) using the avidin-biotin-peroxidase complex (ABC) technique. Twenty-two of the 23 tumours expressed prealbumin, and in 16 of them more than 50% of the tumour cells showed immunoreactivity. The same tumours were subjected to immunostaining with antibodies against low molecular weight keratin, carcino-embryonic antigen, S-100 protein and epithelial membrane antigen for comparison. We conclude that prealbumin, which was absent in 14 adenocarcinomas from other organs, should be included in the panel of markers for differentiating metastatic adenocarcinoma of renal origin from those of other primary tumours.