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Radiotherapy for Pediatric Central Nervous System Tumors – Techniques and Strategies
Published in David A. Walker, Giorgio Perilongo, Roger E. Taylor, Ian F. Pollack, Brain and Spinal Tumors of Childhood, 2020
Embryonal tumors are a heterogeneous group of histologically malignant tumors (WHO grade IV). They are thought to arise from pluripotent stem cells of the CNS and are comprised of small round blue cells on hematoxylin and eosin staining. They share the characteristic of a propensity to disseminate throughout the CNS. The group includes medulloblastomas and a variety of other, more recently recognized entities such as atypical teratoid rhabdoid tumor (ATRT) and embryonal tumor with multilayered rosettes (ETMR). The 2016 World Health Organization Classification of Tumours of the Central Nervous System incorporates both phenotypic and genotypic parameters. The concept of the supratentorial primitive neuroectodermal tumor is no longer recognized, replaced by CNS embryonal tumor (essentially a diagnosis of exclusion). The 2016 classification subdivides medulloblastoma by WNT and SHH activation.26
Rhabdoid Tumor Predisposition Syndrome
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Histologically, atypical teratoid/rhabdoid tumor (Figure 8.1), malignant rhabdoid tumor of the kidney (Figure 8.2), and extrarenal/extracranial rhabdoid tumors share similar morphology. Rhabdoid cytomorphology is common in each of these tumor types. The rhabdoid morphology is characterized by large polygonal cells with vesicular, eccentrically placed nuclei. These nuclei often contain prominent nucleoli. The cytoplasm often contains a single eosinophilic cytoplasmic inclusion that corresponds to the presence of intermediate filaments [27,28]. The tumor classically grows as a discohesive mass of polygonal cells [27,28]. In addition to the classic pattern, some tumors also demonstrate spindled, epithelioid, ovoid, or polygonal shapes [27]. The epithelioid differentiation can be seen as cords and ribbons of cells, to foci of squamoid and glandular epithelium, to poorly differentiated glandular structures [28]. These tumors are infiltrative with lymphovascular invasion, a high proliferative index, and tumor cell necrosis [27,28]. Atypical teratoid/rhabdoid tumors, as briefly mentioned earlier, can demonstrate features of primitive neuroectodermal tumor, which becomes an important differential diagnostic consideration [26,27].
Viral neuro-oncogenesis: Polyomaviruses and brain tumors
Published in Avindra Nath, Joseph R. Berger, Clinical Neurovirology, 2020
Martyn K. White, Sidney E. Croul, Kamel Khalili
Medulloblastoma is a malignant primitive tumor of the cerebellum. Medulloblastoma cerebelli was first described by Bailey and Cushing in 1924 [102], with 29 cases occurring in children of a tumor that arose over the fourth ventricle and projected into the cerebellar vermis. Microscopically, these neoplasms consisted of small undifferentiated cells. Bailey and Cushing assumed that the tumors derived from medulloblasts—embryonal cells with the ability to differentiate into either neurons or glia. Hart and Earle [103] introduced the term primitive neuroectodermal tumor (PNET) for undifferentiated CNS tumors that occur outside the cerebellum but are histologically similar to medulloblastomas. This concept was extended to a variety of pediatric brain tumors including medulloblastomas by Rorke [104] on the grounds that the precursor cells, histology, and clinical course of all these tumors are quite similar. Many authors use the terms medulloblastoma and PNET almost interchangeably as we do in the remainder of this discussion. However, because much remains to be learned about the cellular origins and molecular mechanisms involved in the tumor, there is still controversy surrounding the equivalence of these two classifications.
Epigenetic age acceleration among survivors of pediatric medulloblastoma and primitive neuroectodermal tumor
Published in Pediatric Hematology and Oncology, 2023
Rachel D. Harris, Melissa A. Richard, Maria Monica J. Gramatges, Kevin Wilhelm, Michael E. Scheurer, Philip J. Lupo, Austin L. Brown
Medulloblastoma and primitive neuroectodermal tumor (PNET) are the most common malignant central nervous system (CNS) tumors diagnosed in children.1 Current treatment strategies, consisting of surgery, radiotherapy, and chemotherapy, are associated with long-term survival rates as high as 85%.2 However, these lifesaving therapies can profoundly compromise the long-term function of otherwise healthy organs and tissues. Specifically, long-term survivors of childhood CNS tumors have an elevated risk of multiple chronic health conditions (CHCs), including subsequent neoplasms, neurologic and neurocognitive impairment, endocrine dysfunction, and premature frailty.3–5 For this reason, there is a suspicion that childhood cancer treatment predisposes survivors to an accelerated aging phenotype.4
Primitive neuroectodermal tumor of the pancreas
Published in Baylor University Medical Center Proceedings, 2021
Ted George Achufusi, Raman Sohal, Ernesto Zamora, Prateek Harne, Ronald Russo
Primitive neuroectodermal tumor (PNET), a term coined by Hart and Earle, comprises a group of malignant neoplasms derived from multipotent progenitor cells of neuroectodermal origin.1 Since 1973, when it was first described, <100 cases have been documented.2 PNETs are rapidly growing soft tissue masses, highly malignant and invasive, with a high rate of relapse and a poor prognosis. They are characterized by undifferentiated small round cells that exhibit a neural phenotype. Often these cells resemble other small round cell tumors, so the diagnosis should be confirmed by immunohistochemistry. CD99, a product of the MIC2 gene, is expressed in >95% of Ewing’s sarcoma/PNETs.1,2 Although PNETs can occur in numerous solid organs such as the kidney, ovary, testis, uterus, urinary bladder, parotid gland, heart, lung, rectum, and pancreas, they are extremely rare, and <15 cases of PNET originating from the pancreas have been reported.3 PNETs primarily occur in children and young adults; however, they may present at any age, in any population. Our study reports the case of an otherwise healthy 61-year-old man diagnosed with advanced PNET of the pancreas.
Extraovarian juvenile granulosa cell tumor in a prepubertal child: novel location of a rare tumor
Published in Pediatric Hematology and Oncology, 2020
İdil Rana User, Burak Ardıçlı, Bilgehan Yalçın, Diclehan Orhan, Eren Müngen, Nursun Özcan, Saniye Ekinci
Differential diagnosis of pathologic examination includes germ cell tumor and tumors of adrenal origin when age, clinical presentation and tumor location are considered. Germ cell tumors are stained positive for AFP, glypican 3 and negative for inhibin and calretinin which were contrary to the findings of our patient.7 Microscopic examination showing granular cells, inhibin positivity and MelanA negativity excludes other pathologies and indicate JGCT. PGP9.5 staining is thought to be restricted to tumors of neuroectodermal derivation such as neurobastoma and primitive neuroectodermal tumor. However studies showed mesenchymal tumors, sarcomas and non-neuroendocrine carcinomas are also stained with this marker.8 Similar to our patient, a case report about pubertal girl with mixed sex cord stromal tumor stated positive staining with PGP9.5.9 Presence of PGP9.5 in non-neoplastic Leydig cells, spermatagonia, oocytes, epididymis, ejaculatory duct cells has been shown which may be related to staining in sex cord stromal tumors.8