Cytologic differential diagnosis of myxoid and mucinous neoplasms of the sacrum and parasacral soft tissues

A diagnostically important group of lesions involving the sacrum, spinal canal, and parasacral soft tissues is characterized by a myxoid or mucinous background in cytologic smears. This group of myxoid/mucoid neoplasms includes chordoma, myxopapillary ependymoma, metastatic mucinous adenocarcinoma, and extraskeletal myxoid chondrosarcoma. Despite the similarity of the background substance, each neoplasm within this differential diagnosis has a characteristic composite set of morphologic and immunophenotypic features. Because many of these masses are not easily surgically biopsied, fine-needle aspiration (FNA) is often used for their diagnosis. The private consultation records of the author and the cytology files of the University of Utah Department of Pathology were searched for all lesions arising in or around the sacrum. These cases were reviewed to determine which had a myxoid/mucinous background. Fourteen neoplasms were found and comprise the study set. Four of these cases had cell block material in addition to Diff-Quik-stained smears; a panel of antibodies, including cytokeratin, glial fibrillary acid protein (GFAP), S-100 protein, and carcinoembryonic antigen (CEA), was performed on the cell block material. The smears were evaluated for cytologic features, including the presence of rosette-like structures, physaliphorous cells, gland-like structures, chondroid fragments, "signet ring" and "goblet" cells, as well as the character of the myxoid/mucinous background substance.The cases included one myxopapillary ependymoma, 10 chordomas, two mucinous adenocarcinomas of colonic or gastric origin, and one myxoid chondrosarcoma. Physaliphorous cells were found to be highly specific for chordoma, while a fibrillary myxoid stroma containing cells with elongated cytoplasmic processes and cells lying in a rosette-like pattern around central cores of myxoid to fibrillary stroma were highly characteristic of myxopapillary ependymoma. Fragments of a myxoid/chondroid matrix with lacunar-like spaces strongly supported the diagnosis of myxoid chondrosarcoma. "goblet" or "signet ring" cells with a single distinct vacuole favored mucinous adenocarcinoma. There appear to be sufficient cytomorphologic features present within the FNA smears and cell block material to allow cytologic separation of the more common myxoid and mucinous neoplasms involving the sacral and parasacral tissues.     

Fine-needle aspiration of metastatic sacrococcygeal myxopapillary ependymoma

A 45-yr-old white woman with a 24-yr history of sacrococcygeal myxopapillary ependymoma developed a large metastasis of scalp and skull diagnosed as metastatic ependymoma on fine-needle aspiration, based on cytologic features, histologic pattern in cell block fragments, and a positive reaction with the glial fibrillary acidic protein immunoperoxidase study. The fine-needle study obviated the need for biopsy in this case, for which a surgical approach was considered to be inappropriate due to the extent of the process demonstrated by various imaging techniques.     

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.     

Cytopathologic characteristics and differential diagnostic considerations of osteolytic myxopapillary ependymoma

Myxopapillary ependymoma (MPE) is a rare variant of conventional ependymoma found predominantly in the sacrococcygeal region in young adults and characterized by its distinct epithelial and stromal components (WHO grade I designation). MPE with extensive osteolysis is extremely uncommon and only up to 40 cases have been documented. A case is presented here in which imprint smears of a sacral tumor in an 18‐year‐old man revealed complex papillary structures, small loose clusters, or cord‐like structures of bland tumor cells embedded in a myxoid or mucinous background. The tumor cells possessed uniformly round nuclei with a smooth nuclear outline, fine granular chromatin, and small nucleoli. Slender cytoplasmic fibrillary processes and occasional intracytoplasmic vacuoles were observed. A cytologic diagnosis of a MPE was suggested and histochemical and immunohistochemical studies were conducted on formalin‐fixed, paraffin‐embedded material. Immunohistochemically, the tumor cells showed diffuse and strong membranous and cytoplasmic staining for cytokeratin AE1/AE3, glial fibrillary protein, and S‐100 protein, but negative for epithelial membrane antigen, pan‐neuroendocrine markers (i.e., NSE, chromogranin A, synaptophysin), or brachyury. The proliferative index with MIB‐1 was around 10%. The diagnosis of osteolytic MPE was confirmed based on cytopathologic, histopathological, immunohistochemical results, radiologic findings, and the location of the tumor. We demonstrated here the cytopathological features of osteolytic MPE with emphasis on differential diagnostic considerations. Diagn. Cytopathol. 2014;42:778–783. © 2013 Wiley Periodicals, Inc.     

A 40‐Year‐Old Male with An Intraventricular Tumor

Combined tumors showing histologic features of both ependymoma and subependymoma have been described. In this report we present a case of combined tanycytic ependymoma with foci of subependymoma (WHO grade II), occurring in a 40 year‐old male, which arose in the wall of the lateral ventricle. The tanycytic ependymoma component showed elongated fibrillary cells with a fascicular pattern of growth, while the subependymoma component showed clustered cell bodies surrounded by a fibrillary stroma with a microcystic appearance. We consider the present case to be an unusual example of tanycytic ependymoma; which to the best of our knowledge has not been associated with a subependymoma.     

Highly anaplastic extraventricular ependymoma arising in an adult,mimicking metastatic adenocarcinoma with heavy stromal inflammation and emperiporesis

We report a case of extraventricular ependymoma arising in a 50-year-old woman that took an aggressive clinical course with recurrence three times. The initial tumor was a well-circumscribed nodule in the right temporal white matter measuring 2 cm in diameter. It showed variegated histological findings mimicking metastatic adenocarcinoma: an epithelioid arrangement of highly pleomorphic cells with pseudopapillary structures and perivascular pseudorosettes, and bizarre multinucleated giant cells with occasional emperiporesis surrounded by abundant mononuclear inflammatory cells, as well as a focal small area of conventional ependymoma. Emperiporesis and abundant mononuclear cell infiltration were not previously described in an ependymoma. The recurrent tumors predominantly showed an epithelioid pattern with frequent formation of astroblastoma-like pseudopapillary structures. Neoplastic cells were markedly atypical and had characteristic intracytoplasmic eosinophilic inclusion bodies. Much of the cells in both the initial and recurrent tumors showed a positive immunostaining for glial fibrillary acidic protein (GFAP) with accentuation to the cytoplasmic processes of the pseudorosettes and pseudopapillary structures. Epithelial membrane antigen (EMA) highlighted the epithelial differentiation of the tumor cells, while cytokeratin was completely negative. Although this tumor might be classified to at least WHO grade III from the histology and aggressive behavior, the exact grading is still controversial because of the rarity of such cases.     

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.     

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.     

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.     

Ovarian ependymoma

A 76-year-old woman presented with a large calcifying mass behind the bladder. The tumor contained solid areas of a yellowish white color. Microscopic examination revealed highly cellular solid areas with many typical ependymal perivascular pseudorosettes. The cells contained uniform round-to-oval nuclei, some of which had irregular contours, clumped chromatin and occasional prominent nucleoli. There was widespread geographic necrosis and there were 5 atypical mitotic figures per 10 high power fields. Glial fibrillary acidic protein (GFAP) immunopositivity was observed in the cytoplasm of the tumor cells. Based on the histopathologic and immunohistochemical features, the tumor was diagnosed as an anaplastic ependymoma. This is to the best of our knowledge only the second case of anaplastic ependymoma in the medical literature.     

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).     

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.     

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.     

Papillary ependymoma: its differential diagnosis from choroid plexus papilloma.

Papillary ependymoma is a rare variant of ependymoma and often gives rise to confusion with choroid plexus papilloma because of topographic, light microscopic and ultrastructural similarities. Here, we report two cases of papillary ependymomas regarding their unique clinicopathologic features and differential points from choroid plexus papilloma. Brain MRI revealed a large mass in the left lateral ventricle in one case and a 3cm sized mass in the pineal area and the 3rd ventricle in the other. Microscopically, the tumor was characterized by papillary and tubular structures. Immunohistochemically, the tumor cells in both cases expressed cytokeratins(CK22 and CAM 5.2) but did not express glial fibrillary acidic protein(GFAP), vimentin, epithelial membrane antigen, and S100 protein. This is a very unusual immunohistochemical feature for papillary ependymoma. Ultrastructurally, the tumor showed a mosaic pattern of tumor cells with frequent intercellular microrosettes having a few stubby microvilli, a few cilia and zonulae adherentes. The cytoplasmic processes were markedly reduced compared to conventional ependymoma. The cytoplasm did not contain intermediate filaments. Interestingly, the mitochondria showed abnormal features with a pleomorphic shape and abnormal cristae in both cases. These ultrastructural features enabled differentiation between papillary ependymoma and choroid plexus papilloma in addition to the light microscopic findings.     

Wet SEM: A Novel Method for Rapid Diagnosis of Brain Tumors

The authors present the application of wet SEM for histopathological assessment, a technology for imaging fully hydrated samples at atmospheric pressure in a scanning electron microscope (SEM). Both transmission and scanning electron microscopy techniques usually require long and complex sample preparation of the tissues. In marked contrast, a rapid preparation of tissues is described for evaluation by SEM imaging. The wet SEM technology successfully demonstrated both histological and ultrastructural features of several CNS tumors: Rosette formation and intracytoplasmic lumens were observed in ependymoma; numerous fibrillary processes in fibrillary astrocytoma; and focal rosette formation with no intracytoplasmic lumens in medulloblastoma. Application of this method simultaneously with frozen section may improve rapid intraoperative diagnosis of these intracranial tumors.     

Wet SEM: a novel method for rapid diagnosis of brain tumors

The authors present the application of wet SEM for histopathological assessment, a technology for imaging fully hydrated samples at atmospheric pressure in a scanning electron microscope (SEM). Both transmission and scanning electron microscopy techniques usually require long and complex sample preparation of the tissues. In marked contrast, a rapid preparation of tissues is described for evaluation by SEM imaging. The wet SEM technology successfully demonstrated both histological and ultrastructural features of several CNS tumors: Rosette formation and intracytoplasmic lumens were observed in ependymoma; numerous fibrillary processes in fibrillary astrocytoma; and focal rosette formation with no intracytoplasmic lumens in medulloblastoma. Application of this method simultaneously with frozen section may improve rapid intraoperative diagnosis of these intracranial tumors.     

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.     

Survivin expression in intracranial ependymomas and its correlation with tumor cell proliferation and patient outcome

Survivin expression has been described as prognostic factor in various tumor types and has been shown to correlate with cytologic anaplasia in ependymoma. We immunohistochemically studied survivin expression and its association with Ki-67 and topoisomerase IIalpha (TIIalpha) expression and outcome in 63 patients with intracranial ependymoma. Survivin is expressed in a fraction of nuclei of tumor and endothelial cells including mitotic figures. Survivin indices range from 0.6% to 43.2% and correlate with Ki-67 and TIIalpha indices. On average, 62.86% of Ki-67-expressing tumor cell nuclei coexpress survivin, whereas 92.2% of survivin-expressing nuclei coexpress Ki-67. High survivin, Ki-67, and TIIalpha indices univariately correlated with an unfavorable outcome. In multivariate analysis, only the Ki-67 index remained an independent prognostic factor. In ependymoma, survivin is expressed in a subset of proliferating cells. High survivin expression is associated with poor patient outcome. However, the Ki-67 index is a more accurate prognostic marker than the survivin or TIIalpha index.     

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.     

Parapharyngeal chordoma: A diagnostic challenge and potential mimic of pleomorphic adenoma on fine‐needle aspiration cytology

Chordomas are rare tumors that are usually located in the sacrococcygeal and sphenooccipital region. Their cytologic diagnosis is rather straightforward when sampled by fine‐needle aspiration (FNA) from these characteristic locations, especially when physalipherous cells are present. However, chordomas may pose difficult diagnostic challenges when encountered in unusual locations, such as the parapharyngeal region. We report the cytologic findings of a recurrent chordoma sampled through transoral FNA from the parapharyngeal space of a 66‐year‐old woman. As the prior history of chordoma was not available during the rapid onsite evaluation, the presence of bland epithelioid nonvacuolated cells and spindle cells intimately admixed with a fibrillary, intensely metachromatic material led to an initial diagnosis of pleomorphic adenoma. Review of the patient's prior pathology specimen and of the Papanicolaou‐stained smears and cellblock sections showing rare multivacuolated (physalipherous) cells led to the correct diagnosis, which was supported by immunoperoxidase stains (cytokeratin AE1/AE3+, S100+, GFAP?). A review of the literature found no previous instances in which chordomas mimicked pleomorphic adenoma on FNA. However, since the two tumors show significant cytomorphologic overlap, including the presence of abundant fibrillary matrix with embedded neoplastic cells and single bland spindle and epithelioid tumor cells with occasional intranuclear pseudoinclusions, we compared their cytologic features. A review of the FNA cytologic features of this case of chordoma and of 17 consecutive cases of pleomorphic adenoma found that the presence of a more abundant, focally vacuolated cytoplasm favors chordoma over pleomorphic adenoma. Diagn. Cytopathol. 2013. © 2011 Wiley Periodicals, Inc.