1/20. Relapse of acute myelogenous leukemia as a cerebellar myeloblastoma showing megakaryoblastic differentiation.Myeloblastomas (granulocytic sarcomas) occurring within the central nervous system (CNS) are extremely rare lesions that may develop in patients with acute or chronic myeloproliferative disorders. The majority of such lesions involve brain or spinal cord by contiguous spread from meningeal or bony sites, rather than originating within the CNS parenchyma. We describe a patient with acute myelogenous leukemia in remission, who developed a purely intraparenchymal cerebellar myeloblastoma with megakaryocytic differentiation. The neoplastic cells expressed the megakaryocytic markers factor viii-related antigen and platelet glycoprotein-IIIa (CD61), and showed ultrastructural features that were indicative of megakaryocytic differentiation. Clinically, myeloblastomas of the CNS invoke a broad differential diagnosis that includes abscess, hemorrhage, and metastatic neoplasms because of their intraparenchymal location and radiologic features. Although they are rare, myeloblastomas should be included in the histopathologic differential diagnosis of a poorly differentiated neoplasm occurring within the CNS, particularly in a patient with a history of myeloproliferative or myelodysplastic disease.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
2/20. Signet-ring cell ependymoma: case report with implications for pathogenesis and differential diagnosis.We describe light microscopic, immunohistochemical and ultrastructural features of a signet-ring cell ependymoma (WHO grade II) identified in a surgically resected left cerebellar cystic tumor from a 64-year-old man. Part of the tumor showed clear-cell differentiation. Immunohistochemical coexpression of glial fibrillary acidic protein and epithelial membrane antigen, characteristic of ependymoma, was detected in both components. Sinuous intermediate junctions, cytoplasmic lumina, and scant astroglial filaments were demonstrated by electron microscopy. Signet-ring cell change was shown to be induced by disproportionate cavitation of either microvillus-bearing cytoplasmic lumina or microrosettes. The staining qualities of clear cells were mainly due to paucity and degeneration of subcellular organelles. Therefore, signet-ring cell ependymomas represent a unique anomaly of intra- and extracellular compartmentalization to be distinguished from various unrelated forms of cytoplasmic volume increase, resulting in an optically similar "empty" appearance of tumor cells. As a clinically relevant consequence, signet-ring cell ependymoma must be included in the differential diagnosis of primary or metastatic neoplasms of the central nervous system, having in common a phenotype characterized by overdeveloped optically lucent cell bodies.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
3/20. Primary Ki-1 lymphoma in the central nervous system.Large cell anaplastic malignant lymphoma with Ki-1 (CD30) antigen is a new entity among human non-Hodgkin's malignant lymphomas according Updated Kiel classification and is also a very rare subtype in primary central nervous system (CNS) malignant lymphomas. The precise clinical characteristics and the significance of Ki-1 antigen have yet to be clarified. The authors herein report a case of Ki-1 positive primary T-cell CNS malignant lymphoma. A 49-year-old man presented with multiple mass lesions in the brain on MRI. Immunohistochemical investigations of biopsy specimens from the superior medullary velum revealed a large cell anaplastic T-cell lymphoma positive for Ki-1 antigen. After administering extensive chemo-radiotherapy, the patient has survived for more than 42 months after the onset of symptoms.- - - - - - - - - - ranking = 3keywords = antigen (Clic here for more details about this article) |
4/20. Cerebellar degeneration and autoimmunity to zinc-finger proteins of the cerebellum.The serum of a patient with subacute cerebellar dysfunction was used to probe a cDNA expression library and isolate two genes: Zic1 (zinc-finger of the cerebellum) and Zic4. The patient had intrathecal synthesis of Zic antibodies, suggesting that the Zic proteins were autoantigens of the neurologic disorder. The Zic proteins are involved in cerebellar development and are reported as being preferentially expressed by medulloblastomas. It was found that the expression of Zic proteins is enriched in, but not limited to, medulloblastomas and primitive neuroectodermal tumors.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
5/20. Immunocytochemical demonstration of interphotoreceptor retinoid-binding protein in cerebellar medulloblastoma.Previously, immunoreactive rod-opsin and S-antigen (arrestin), two highly characteristic markers of retinal photoreceptors and pinealocytes, were shown to be present in certain medulloblastoma cells. It, thus, has been suggested that such cells differentiate along the photoreceptor lineage. This is corroborated in the present immunocytochemical investigation using antibodies against another photoreceptor-cell marker, the interphotoreceptor retinoid-binding protein (IRBP). As shown in preparations of human retina and pineal organ, IRBP can be successfully demonstrated in formalin-fixed and paraffin-embedded tissue: the IRBP immunoreaction is located to the outer and inner segments of retinal photoreceptor cells and to perikarya of certain pinealocytes. Examination of formalin-fixed, paraffin-embedded biopsy specimens of 66 cerebellar medullo-blastomas revealed varying numbers of IRBP-immuno-reactive tumor cells in 19 cases that were formerly shown to contain rod-opsin and S-antigen immunoreaction. IRBP-immunoreactive tumor cells were also found in a retinoblastoma and a pineocytoma, but not in neuroblastoma, ganglioneuroblastoma, glioblastoma, oligodendroglioma and astrocytoma. The results indicate: (1) cerebellar medulloblastomas are heterogeneous in their differentiation potential; (2) one type of medulloblastoma displays photoreceptor characteristics; (3) this type appears to be closely related to retinoblastoma and pineal cell tumors; and (4) all three types of tumors may display additional common features to be explored in future studies.- - - - - - - - - - ranking = 2keywords = antigen (Clic here for more details about this article) |
6/20. Epithelial differentiation in medulloblastoma: comparison with other embryonal tumors of neuroectodermal origin.Three cases of medulloblastoma characterized by epithelial differentiation are described in patients 6-months-, 1-month- and 8-years-old. Histologically, tumors from the two infant patients showed a perivascular arrangement without apparent radiated cytoplasmic processes from the vessels. Tumor cells displayed round and/or pleomorphic vesicular nuclei and a more abundant eosinophilic cytoplasm than that found in classic medulloblastoma. Neither Homer-Wright rosettes nor ependymal or ependymoblastic rosettes were noted in these tumors. The tumor in the 8-year-old patient exhibited a classic medulloblastoma component intermingled with abundant eosinophilic cytoplasm forming a tubular structure. Immunohistochemically, tumor cells in all cases were positive for cytokeratin, synaptophysin, and vimentin. In the third case involving the 8-year-old patient, epithelial tumor cells were positive for cytokeratin, whereas classic medulloblastoma components were negative for cytokeratin. Positive staining for melanoma-specific antigen was seen only in the third case, where strong reactivity of tumor cells formed a tubulus. However, the classic medulloblastoma component was negative for melanoma-specific antigen. Ultrastructurally, basal laminae were observed around tumor cells in the 6-month-old patient. These morphological and immunohistochemical features suggest that medulloblastoma with epithelial differentiation is a rare but distinct variant of medulloblastoma, and that some of these tumors should show differentiation in ocular pigment epithelium.- - - - - - - - - - ranking = 2keywords = antigen (Clic here for more details about this article) |
7/20. Solitary fibrous tumor of the cerebellopontine angle with salivary gland heterotopia: a unique presentation.We report the unique association of a solitary fibrous tumor of the cerebellopontine angle with ectopic salivary gland tissue in a 53-year-old woman. The patient, diagnosed 21 years earlier with a right cerebellopontine angle fibrous meningioma, presented with a recurrent mass, which, upon surgical removal, showed features of a solitary fibrous tumor. Strong and diffuse immunoreactivity to CD34 and BCL-2 and a negative epithelial membrane antigen immunostain confirmed the diagnosis. Admixed with the spindle cell neoplasm, a bland glandular element composed of small glands and variably dilated tubules was noted. The vague tubuloacinar arrangement of the glands and the presence of acinar cells with a granular, periodic acid-Schiff-positive, basophilic cytoplasm, resembling serous type acini, were features of benign, although ectopic, salivary gland tissue. The presence of a myoepithelial cell layer, surrounding some of the acini and highlighted by the smooth muscle actin immunostain, strengthened this interpretation.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
8/20. Cerebellar metastases from prostatic carcinoma.A 67-year-old man presented with worsening headaches and gait disturbance, and with minimal clinical signs. A brain MRI showed multiple solid cerebellar metastases. The pathological diagnosis of metastatic carcinoma of the prostate was further suggested by an elevation in prostate specific antigen, and was pathologically confirmed following the neurosurgical removal of the tumours. The rarity of this presentation, as documented in the clinical literature, is reviewed.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
9/20. Pediatric embryonal tumor of the cerebellum with rhabdoid cells and novel intracytoplasmic inclusions: distinction from atypical teratoid/rhabdoid tumor.We report a case of embryonal tumor with novel inclusion bodies occurring in the cerebellum of a 12-year-old girl. The tumor was histopathologically composed of small undifferentiated cells intermingled with a small number of rhabdoid cells, which had an ultrastructural feature of intermediate filament whorls. Immunohistochemically, the neoplasm showed a polyphenotype, including glial fibrillary acidic protein (GFAP), S-100, synaptophysin, chromogranin a, cytokeratin, vimentin, smooth muscle actin, and desmin. However, epithelial membrane antigen (EMA) immunoreactivity was absent. The MIB-1 labeling index was high (25.6%). Ultrastructurally, there was no evidence of neuronal or myogenic differentiation. The small neoplastic cells contained numerous small intracytoplasmic inclusions stained pink by eosin and red by Masson's trichrome stain. The inclusion body was a densely packed, granulovesicular structure at the electron microscopic level, and was immunoreactive for vimentin, GFAP, desmin, and actin. reverse transcription-PCR and immunohistochemistry showed the expression of INI1 at the rna and protein levels, respectively. In conclusion, this tumor was differentiated from atypical teratoid/rhabdoid tumor by the absence of EMA and the presence of INI1 mRNA and protein, and diagnosed as an unclassified, embryonal tumor. Eosinophilic, granulovesicular inclusions of the tumor cells are novel cytoplasmic inclusions in the brain tumor.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
10/20. medulloblastoma simulating acute myeloid leukemia: case report with a review of "myeloid antigen" expression in nonhematopoietic tissues and tumors.medulloblastoma is a primitive neuroectodermal tumor arising in the posterior fossa usually in the first decade of life. Systemic metastases are infrequent at diagnosis and usually occur after surgical resection or shunt placement. We report a rare case of medulloblastoma in an 18-year-old woman who presented with headache, leukopenia, and anemia. neurologic examination was normal. bone marrow evaluation revealed primitive cells morphologically resembling blasts. By flow cytometry, these cells lacked CD45 and expressed CD13/33, CD15, CD34, HLA-DR, and strong CD56. The presence of myeloid antigens and CD34 suggested acute myeloid leukemia; however, the bone marrow core biopsy architecture and tumor cells in cerebrospinal fluid were more compatible with a nonhematopoietic tumor. Further workup revealed a cerebellar mass, and a diagnosis of desmoplastic medulloblastoma was made. To our knowledge, this is the first reported case of a nonhematopoietic small round blue-cell tumor expressing multiple myeloid antigens and CD34 by flow cytometry.- - - - - - - - - - ranking = 6keywords = antigen (Clic here for more details about this article) |
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