Medulloblastoma tumors

In medulloblastoma tumors in humans, misregulation of H3K9 methylation is implicated as a carcinogenic event with L3MBTL3 possibly serving as a tumor suppressor as evidenced by its deletion in some medulloblastoma cell lines [21]. 

Neuroblastomas are small, round, blue cell tumors that may arise in the adrenal gland and a variety of extra-adrenal sites. The differential diagnosis is wide and includes rhabdomyosarcoma, Ewing s sarcoma-primitive neuroectodermal tumor (ES-PNET), medulloblastoma, small cell osteosarcoma, lymphoblastic lymphoma, blastematous Wilms tumor, and small cell desmoplastic tumor. Numerous markers have been used for the diagnosis of neuroblastomas including NE markers, cytoskeletal proteins, catecholamine-synthesizing enzymes, and neuroblastoma-"specific antibodies (Eig. 

Burger PC, Yu IT, Tihan T, et al. Atypical teratoid/rhabdoid tumor of the central nervous system a highly malignant tumor of infancy and childhood frequently mistaken for medulloblastoma a Pediatric Oncology Group study. Am J Surg Pathol. 1998 22 1083-1092. 

Synaptophysin/BioCenex/1 600 Neuronal and pineal tumors PNET medulloblastoma Mw 10 min in citrate, pH 6.0... 

Pineoblastoma resembles medulloblastoma (Fig. 20.38 see Fig. 20.21) except for its origin in the pineal gland (see Table 20.8). Fibrillary rosettes may be evident and are more common than Flexner-Wintersteiner rosettes. Synaptophysin is most useful in identifying neuronal differentiation in these tumors (see Fig. 20.38A) because NF immunoreactivity is often negative (Box 20.3). Some tumors express retinal-S antigen. It would be interesting to know whether this sight-specific marker is more common in pineoblastomas than in other medulloblastomas. 

The medulloblastoma is a primitive neuroectodermal tumor that arises in the cerebellum or in the roof of the fourth ventricle (see Box 20.3, Fig. 20.21, and Table... 

Protein gene product 9.5 (PGP 9.5) is described in texts as another marker of neuronal differentiation of these tumors. S-100 protein may be found in medulloblastomas. In this author s experience, finding PGP 9.5, NSE, and S-100 protein must be carefully interpreted because of its presence in other neoplasms in the differential diagnosis, including most gliomas and some carcinomas. These markers seem to work better for peripheral neuroblastomas than for medulloblastomas. Staining for synaptophysin and the presence of fibrillar cellular processes works best (see Fig. 20.21B). Difficult cases can be examined for their ultrastructure. 

FIGURE 20.39 This desmoplastic medulloblastoma shows pale islands on H E (A) that contain synaptophysin-positive cells (B). Adjacent sections of the same region of tumor show that densely crowded cells form reticulin-positive bands (C) around the pale islands and that these bands contain most of the MIBl -positive cells (D). 

The features and differential diagnosis of central nervous primitive neuroectodermal tumor (cPNET) can be found in the Medulloblastoma section earlier in this chapter. Although cerebral PNET, cerebellar medulloblastoma, and pineoblastoma are all primitive neuroectodermal tumors by histology alone, the recent tendency has been to recognize the cerebral tumor as a PNET, the posterior fossa tumor as a medulloblastoma, and the pineal tumor as a pineoblastoma (see Box 20.3). It is this author s opinion that these tumors are all different and that their differences will eventually be revealed with better markers. The cerebral ganglioneuroblastoma and neuroblastoma are called PNET with advanced neuronal differentiation. ... 

The medulloblastoma is a CNS primitive neuroectodermal tumor (cPNET) in the cerebellum. The most frequent genetic abnormality associated with medulloblastoma is loss of chromosome arm 17p. This is often seen as an isochromosome 17q (one chromosome composed... 

Earlier in this chapter, I introduced Ei-Fraumeni syndrome (EPS), a germline mutation of the p53 gene on the short arm of chromosome 17. Medulloblastoma and PNET account for about 10% of all brain tumors associated with a germline mutation of the p53 gene... 

Raimondi AJ, Tomita T The disadvantages of prophyiactic whole CNS postoperative radiation therapy for medulloblastoma, in Multidisciplinary Aspects of Brain Tumor Therapy. Edited by Paoletti P, Walker MD, Butti G, et al Amsterdam, Elsevier, 1979, pp 209-218... 

Further investigation of the B. antidysenterica extract [10] led to the isolation of three new quassinoids bmceanol-D (17), -E (18), -F (19), and known a diSsmoiAs yadanzioside-N A), bruceantin (1), and isobnicein-B (5). Bruceanol-D (17) and -F (19) were both obtained as colorless amorphous solids and bruceanol-E (18) was obtained as colorless needles. They showed cytotoxicity for tumor cells such as KB (nasopharynx carcinoma), A-549 (human lung carcinoma), HCT-8 (human colon tumor), P-388 (murine lymphocytic lei emia), TE-671 (human medulloblastoma), and RPMI-7951 (human melanoma), as shown in Table 1. 

---