Squash cytology of tanycytic ependymoma: A report of two cases

Tanycytic ependymoma is a rare variant of ependymoma which has a predilection for the spinal cord. It is a WHO grade II tumour with favourable outcome. Although squash cytology of ependymoma is well described, there is sparse literature available on squash cytomorphology of tanycytic variant. Here we present two cases of squash cytology of tanycytic ependymoma. In the first case the diagnosis of tanycytic ependymoma was considered. However, in the second case a diagnosis of usual ependymoma was offered. Subsequently histopathology confirmed tanycytic nature in both the cases. In this article we discuss the squash cytological features of tanycytic ependymoma along with its differential diagnosis. Diagn. Cytopathol. 2017;45:270–273. © 2016 Wiley Periodicals, Inc.     

Recurrent subependymoma of fourth ventricle with unusual atypical histological features: A case report

Subependymoma is a rare subtype of benign ependymal neoplasm with distinct histological features. Anaplastic transformation has not yet been reported in this tumor to date. We present here a very unusual case of a 62‐year‐old woman with recurrent subependymoma of the fourth ventricle with multiple atypical histological features. Histologically, the resected recurrent tumor showed characteristic small cell clusters and nests of ependymal cells with an interspersed gliofibrillary matrix as seen in a classic subependymoma. In addition, there were very unusual histological features, including multiple areas of necrosis, microvascular proliferation, thrombosed blood vessels, and scattered mitotic figures. No coexisting ependymoma component of higher World Health Organization (WHO) grade was present. Immunohistochemically, MIB‐1 labeling index was high, with up to 15% in the highest areas. Review of this patient's initial tumor, which was resected 6 years prior to recurrence, demonstrated features of a typical classic subependymoma without atypical features or a secondary tumor component. Subependymomas are known to be low‐grade tumors and are usually cured if completely excised. The tumor presented here is unique in that several atypical pathological features were found in an otherwise typical subependymoma. Our case may represent anaplastic transformation of subependymoma, although no such examples have been reported to date.     

Tanycytic ependymoma in a 76-year-old Puerto Rican male

Ependymoma is a slowly growing tumor in children and young adults originating from the wall of the ventricles or from the spinal canal that is composed of neoplastic ependymal cells. Tanycytic ependymoma is a rare variant of ependymoma usually arising in the intra medullary spine. The World Health Organization classifies the tanycytic ependymoma as a grade II tumor. The diagnosis of tanycytic ependymoma is challenging since the morphology of the lesions resemble those found in schwannoma and astrocytomas. In the present study, we show a case of a 76 years old male with a progressive paraparesis for 8 years, due to a spinal tumor. Radiological and histological studies were used to classify the tumor as tanycytic ependymoma. Therefore, it is important to be aware of tanycytic ependymoma and its immunohistochemistry profile in older patients, especially within the Caribbean Hispanic population. To our knowledge this is the oldest patient known to have this rare tumor and the first case reported in Puerto Rico.     

Histological characterization of an ependymoma in the fourth ventricle of a cat

A tumour occupying the fourth ventricle in a 3-year-old cat was removed surgically and characterized as a tanycytic ependymoma on the basis of histological features of low cellularity, inconspicuous perivascular pseudorosettes and fascicular architecture. Immunohistochemical analysis of sections revealed that the neoplastic cells were immunoreactive for glial fibrillary acidic protein (GFAP), vimentin and S-100. The histological and immunohistochemical findings were similar to those of human tanycytic ependymoma, a subclassification of ependymoma not previously described in domestic species.     

Rapid spontaneous malignant progression of supratentorial tanycytic ependymoma with sarcomatous features – “Ependymosarcoma”

By analogy to gliosarcoma, the term “ependymosarcoma” has recently been coined to thematize the rare phenomenon of a malignant mesenchymal component arising within an ependymoma. We report on an example of this paradigm, involving tanycytic ependymoma as the host tumor in a 40-year-old female who underwent two tumor extirpation procedures at one-year interval. She first presented with severe headaches, and was seen by imaging to harbor a moderately enhancing mass 2.5 cm in diameter at the rostral septum pellucidum accompanied by occlusive hydrocephalus. Microscopically, the tumor consisted of solid, wavy fascicles of elongated cells that were occasionally interrupted by vague perivascular pseudorosettes. Mitotic activity was absent, and less than 1% of nuclei immunoreacted for MIB-1. A histological diagnosis of tanycytic ependymoma (WHO grade II) was rendered, and no adjuvant therapy given. At recurrence, the lesion was 3.5 cm in diameter, intensely enhancing, and had already seeded into the subarachnoid space. Histology showed a biphasic glial–sarcomatous architecture with remnants of the original ependymoma now displaying hypercellularity and atypical – yet not frankly anaplastic – features. The sarcomatous moiety consisted of spindle and epithelioid cells densely interwoven with reticulin fibers. While the ependymal component was GFAP and S100 protein positive, and featured punctate staining for EMA, none of these markers was expressed in the adjacent sarcoma. Instead, the latter reacted for vimentin and smooth muscle actin. To the best of our knowledge, this is the first documentation of tanycytic ependymoma undergoing malignant transformation, one driven by a highly anaplastic mesenchymal component, corresponding to “ependymosarcoma”.     

Tanycytic Ependymoma

Tanycytic ependymoma is an uncommon fibrillar variant of ependymoma characterized by streams of piloid, or hair-like, cells having “ependymal” nuclei. True ependymal rosettes are absent, and perivascular rosettes are inconspicuous. Misinterpretation as schwannoma or astrocytoma is a diagnostic problem and well-documented cases are scarce. The purpose of this report is to document the ependymal features of the neoplasm and to increase awareness of the entity's existence. Biopsy tissues from three patients with tanycytic ependymoma were examined. All tumors consisted of sheets of spindle cells that were positive for glial fibrillary acidic and S-100 proteins. Ultrastructural examination showed characteristic ependymal features, including intracytoplasmic intermediate filaments, prominent intercellular junctions, numerous slender surface microvilli, and microvilli-lined lumina. Accurate recognition of the ependymal nature of this spindle neoplasm requires a high index of suspicion. Because the spindle cells are immu-noreactive with antibodies to both glial fibrillary acidic and S-100 proteins, ultrastructural confirmation of ependymal features is necessary.     

Intraoperative diagnosis of tanycytic ependymoma: pitfalls and differential diagnosis

Smear preparations have become increasingly popular in the intraoperative assessment of central nervous system pathology. The cytological features of a histologically proven tanycytic ependymoma are presented with the pitfalls and differential diagnosis. The smear preparation showed a glial neoplasm composed of cells with long, bipolar glial processes and oval to spindle-shaped nuclei resembling those seen in pilocytic astrocytoma smears. The smear characteristics of an ependymoma usually show remarkably uniform round-to-oval nuclei, fluffy glial processes, and a perivascular nuclear-free zone (pseudorosetting). None of these features were present in our case. The accompanying frozen section showed a fascicular spindle-cell tumor that resembled a schwanomma, a commonly reported misinterpretation of the histology of tanycytic ependymomas on frozen sections. Careful attention to the radiological findings, the surgeon's impression, and the intraoperative smear preparation details should allow one to include this uncommon entity in the differential diagnosis of spinal neoplasms.     

伸长细胞型室管膜瘤2例报道及文献复习

目的探讨伸长细胞型室管膜瘤的病理形态学特征。方法复习2例伸长细胞型室管膜瘤的临床病理资料，对手术切除的肿瘤组织，常规石蜡切片，HE染色，光镜观察，同时进行免疫组织化学标记GFAP、EMA、S-100蛋白、CKpan、Syn、CD34。结果例1位于腰2～3椎管内终丝，临床上主要表现出脊髓压迫症状，如运动及感觉障碍；例2发生于侧脑室，主要表现为头痛、呕吐、视物模糊。病理组织学上肿瘤富于细胞，排列成束状、交织状，细胞胞突细长双极，核异型性小，少数肿瘤细胞围绕血管周围形成室管膜瘤的无核区结构。免疫组化显示肿瘤细胞表达GFAP、EMA、CD99，而S-100蛋白阴性。结论伸长细胞型室管膜瘤是室管膜瘤的一种罕见亚型，病理诊断时尤其应注意与椎管内的神经鞘瘤和星形细胞瘤鉴别。     

Tanycytic ependymoma: two case reports and review of the literature

Two cases of tanycytic ependymoma are reported, one in a woman aged 33 years and one in a man aged 36 years. The woman presented with lesions at L2 and L3 in the spinal cord and clinical symptoms suggested spinal cord compression, such as movement and sensory dysfunction. The man had a lesion located in the lateral ventricle and presented with headache, vomiting, and impaired vision. Both of these patients developed gradual increases in the intensity of their symptoms over a few months prior to admission. A spinal cord MRI of the woman showed a well-defined, solid cystic mass measuring 1.0 × 6.5 cm at L2 and L3 of the spinal cord. The mass showed low signal intensity on T2-weighted images in the intervertebral disc with equal signal intensity T1-/T2-weighted images. The signal was uniform and enhanced scanning showed a light strengthening of signal. A brain MRI of the man showed a well-defined mass measuring 4 cm in diameter invading the right ventricle. The mass showed low signal intensity on right T1-weighted images and high signal intensity on T2-weighted images. Histopathologically, the tumors were rich with significant and uniform proliferation of long spindle cells, which were arranged in fasciculate and knitted patterns with bipolar and spindled processes focally forming perivascular pseudorosettes. The cell nuclei showed minor pleomorphism. A few tumor cells centered on the vessels resulted in a nuclear-free zone, which was characteristic of ependymoma. Immunohistochemically, the tumor cells were positive for GFAP, EMA, and CD99, but negative for S-100. A review of the cases reported in the literature shows that tanycytic ependymoma occurs more often in the spinal cord. As it can resemble pilocytic astrocytoma and schwannoma, tanycytic ependymoma should be differentially diagnosed to exclude some of the benign spindle cell tumors of the central nervous system.     

cIMPACT‐NOW update 7: advancing the molecular classification of ependymal tumors

Advances in our understanding of the biological basis and molecular characteristics of ependymal tumors since the latest iteration of the World Health Organization (WHO) classification of CNS tumors (2016) have prompted the cIMPACT‐NOW group to recommend a new classification. Separation of ependymal tumors by anatomic site is an important principle of the new classification and was prompted by methylome profiling data to indicate that molecular groups of ependymal tumors in the posterior fossa and supratentorial and spinal compartments are distinct. Common recurrent genetic or epigenetic alterations found in tumors belonging to the main molecular groups have been used to define tumor types at intracranial sites; C11orf95 and YAP1 fusion genes for supratentorial tumors and two types of posterior fossa ependymoma defined by methylation group, PFA and PFB. A recently described type of aggressive spinal ependymoma with MYCN amplification has also been included. Myxopapillary ependymoma and subependymoma have been retained as histopathologically defined tumor types, but the classification has dropped the distinction between classic and anaplastic ependymoma. While the cIMPACT‐NOW group considered that data to inform assignment of grade to molecularly defined ependymomas are insufficiently mature, it recommends assigning WHO grade 2 to myxopapillary ependymoma and allows grade 2 or grade 3 to be assigned to ependymomas not defined by molecular status.     

伸展细胞型室管膜瘤的临床病理特点

目的：观察一少见的特殊类型室管膜瘤的临床病理特点,拟译名为伸展细胞型室管膜瘤。方法：复习3例此型的临床病理和免疫组化资料及有关文献。结果：3例肿瘤均位于脊髓内。它们的临床表现和放射影像学与室管膜瘤其他类型表现相同,病理形态学上,瘤细胞呈现双极的长梭形胶质细胞,形成不典型的血管周菊形团,GFAP、EMA弱阳性,而vimentin强阳性,而可与星形细胞瘤及神经鞘瘤相鉴别,其预后与其他类型室管膜瘤相类似。结论：由于肿瘤由双极、长梭形细胞组成。及tanycyte来源于tanyos有stretch伸出展开之意,“tanycytic ependymona ”以译成“伸展细胞型室管膜瘤”为妥。     

Pigmented ependymoma with lipofuscin and neuromelanin production

We report an unusual case of ependymoma with pigmentation, a phenomenon that has only been described in a few cases, to our knowledge. This tumor occurred in the fourth ventricle of a 45-year-old man. It showed the typical histologic appearance of ependymoma with perivascular pseudorosettes and rare ependymal rosettes. Some tumor cells contained brown cytoplasmic pigment, which was shown histochemically to represent a mixture of lipofuscin and neuromelanin. The pigment was positive for acid-fast and periodic acid-Schiff stains and was also focally positive for Masson-Fontana and Schmorl stains (bleached by pretreatment with potassium permanganate). In addition, some other tumor cells showed a signet ring morphology as a result of prominent intracytoplasmic vacuolation. Immunohistochemically, all the tumor cells expressed glial fibrillary acidic protein, and rare pigmented tumor cells also expressed HMB-45. Ultrastructural examination showed irregularly shaped heterogeneous electron-dense bodies corresponding to the pigment, and the cytoplasmic vacuoles were formed by dilatation of intracytoplasmic lumens lined by microvilli. Since lipofuscin production can occur in normal ependymal cells and neuromelanin has been suggested to be a melanized form of lipofuscin, it is not surprising that these 2 pigments can be found in ependymoma. In all the previously reported cases, the pigment was shown to represent melanin only. In our case, the HMB-45 positivity in rare tumor cells indicated that there might also be a minor melanin component in the pigment in addition to lipofuscin and neuromelanin.     

Giant cell ependymoma-report of three cases and review of the literature

Ependymomas constitute the most common type of primary spinal cord tumors, and are subclassified as myxopapillary ependymoma, classic ependymoma, and anaplastic ependymoma. Ependymomas can be further subclassified based on morphologic phenotype: cellular, papillary, tanycytic, clear cell, pigmented and epithelioid. Giant cell ependymoma (GCE), a rare variant, has recently been described. Reported cases have exhibited a wide anatomic distribution, including spinal cord, cerebrum and cerebellum. We report here three cases of GCE, arising from cerebrum in a 5-year-old girl, spinal cord in a 34-year-old female and cerebellum in an 86-year-old female respectively. Histologically those cases showed prominent pleomorphic giant cells with focal perivascular pseudorosettes in all cases. Tumor cells were immunopositive for GFAP and EMA. Only the first case was qualified for anaplastic ependymoma. No recurrence was noted in these three cases after 57, 46 and 6 months of follow-up respectively. By reviewing the literature, GCEs arising from spinal cord and cerebellum tended to have low-grade morphology while supratentorially located GCEs tended to have anaplastic features. GCEs were preferentially located in extraventricular regions. Anaplastic GCEs in adult population seemed to pursue a more aggressive behavior. Gross total resection should still be the main treatment for GCEs.     

Ectopic cervical anaplastic ependymoma

Ependymomas generally arise in the central nervous system (CNS), although rare primary extraneural ependymomas have been observed. Reported herein for the first time is the case of a patient with primary ectopic cervical anaplastic ependymoma. The tumor was found in the right neck root region of a 35-year-old man. No additional tumor was found in the CNS or in other parts of the body. The patient received surgery and post-surgical local radiotherapy. Microscopically, the tumor consisted of round to oval cells with fine chromatin, distinct nucleoli, moderate nuclear atypia and numerous mitoses (>25/10 high-power fields) in a densely cellular growth pattern with characteristic fibrillary cytoplasm and formation of perivascular pseudorosettes. By immunohistochemistry, the tumor cells were positive for glial fibrillary acidic protein, epithelial membrane antigen (EMA), vimentin and S-100 protein. EMA staining showed a membranous as well as a paranuclear pattern of immunoreactivity. Electron microscopic studies revealed that tumor cells form micro rosettes, into which microvilli and cilia projected. The diagnosis was World Health Organization grade III anaplastic ependymoma. There is no evidence of local tumor recurrence or distant metastasis after 30 months follow up. The present case adds yet another unique example to the already diverse spectrum of head and neck neoplasms encountered in surgical pathology.     

Clear-cell Ependymoma of the Cerebellum: A Case Report

A case of clear-cell ependymoma occurring in the cerebellum of a 3-year-old girl is reported. Light-microscopically, the tumor consisted mainly of clear cells with a perinuclear halo and showed some vague perivascular pseudorosettes, not true rosettes. In addition, the histological features of anaplasia, characterized by increased mitosis and focal pseudopalisading necrosis, were also observed. Immunohistochemically, the tumor cells were focally positive for glial fibrillary acidic protein and weakly positive for epithelial membrane antigen. Ultrastructurally, the intermediate junctions and rudimentary cilia confirmed the ependymal differentiation. Fifteen cases of infratentorial clear-cell ependymoma have been reported to date, and this case is the second childhood tumor among them, to the best of the authors' knowledge.     

Pelvic ependymoma arising from the small bowel

A 37-year-old woman underwent resection of an abdominal tumour which was adherent to the wall of the ileum. The diagnosis of an ependymoma was supported by evidence of typical perivascular pseudorosettes which stained positive for glial fibrillary acidic protein and contained abundant intermediate filaments within the elongated processes by electron microscopy. Flow cytometric study showed a diploid population of tumour cells. This is the first case of an ependymoma arising from the small bowel without any connection to the genital tract, the omentum or with the sacroccygeal area. As is the case with other unusual and ectopic localisations of ependymomas, prognosis of this tumour is difficult to evaluate.     

SUBCUTANEOUS SACROCOCCYGEAL MYXOPAPILLARY EPENDYMOMA A Case Report and Review of the Literatures

A case of myxopapillary ependymoma originating in the soft tissue is described. The tumor was located subcutaneously over the coccyx of an 11-year-old girl but was connected neither to the filum terminale nor cauda equina. Clinically, the tumor was locally resected with a diagnosis of pilonidal cyst. Histological and electron microscopic findings were identical to myxopapillary ependymoma. The tumor cells showed a positive reaction by immunoperoxidase method (PAP method) of glial fibrillary acidic protein (GFAP). ACTA PATHOL. JPN. 35 : 925–931, 1985.     

Subcutaneous sacrococcygeal myxopapillary ependymoma. A case report and review of the literatures

A case of myxopapillary ependymoma originating in the soft tissue is described. The tumor was located subcutaneously over the coccyx of an 11-year-old girl but was connected neither to the filum terminale nor cauda equina. Clinically, the tumor was locally resected with a diagnosis of pilonidal cyst. Histological and electron microscopic findings were identical to myxopapillary ependymoma. The tumor cells showed a positive reaction by immunoperoxidase method (PAP method) of glial fibrillary acidic protein (GFAP).     

Clear-cell ependymoma of the cerebellum: a case report

A case of clear-cell ependymoma occurring in the cerebellum of a 3-year-old girl is reported. Light-microscopically, the tumor consisted mainly of clear cells with a perinuclear halo and showed some vague perivascular pseudorosettes, not true rosettes. In addition, the histological features of anaplasia, characterized by increased mitosis and focal pseudopalisading necrosis, were also observed. Immunohistochemically, the tumor cells were focally positive for glial fibrillary acidic protein and weakly positive for epithelial membrane antigen. Ultrastructurally, the intermediate junctions and rudimentary cilia confirmed the ependymal differentiation. Fifteen cases of infratentorial clear-cell ependymoma have been reported to date, and this case is the second childhood tumor among them, to the best of the authors' knowledge.     

Cerebral myxopapillary ependymoma.

A rare case of myxopapillary ependymoma is reported. The tumor occurred in the cerebral hemisphere of an 8-year-old girl and had no relationship to the lateral ventricles. Microscopically, it showed abundant mucin production around papillary or reticular structures. Immunohistochemically, these tumor cells were weakly positive, with glial fibrillary acidic protein demonstrated in part of the tumor and vimentin strongly demonstrated throughout the tumor. The results may indicate the poorly differentiated nature of this tumor. This is the second reported case of intracranial myxopapillary ependymoma.