Treatment of Pediatric Low-Grade Gliomas.

PURPOSE OF REVIEW: Pediatric low-grade gliomas and glioneuronal tumors (pLGG) account for approximately 30% of pediatric CNS neoplasms, encompassing a heterogeneous group of tumors of primarily glial or mixed neuronal-glial histology. This article reviews the treatment of pLGG with emphasis on an individualized approach incorporating multidisciplinary input from surgery, radiation oncology, neuroradiology, neuropathology, and pediatric oncology to carefully weigh the risks and benefits of specific interventions against tumor-related morbidity. Complete surgical resection can be curative for cerebellar and hemispheric lesions, while use of radiotherapy is restricted to older patients or those refractory to medical therapy. Chemotherapy remains the preferred first-line therapy for adjuvant treatment of the majority of recurrent or progressive pLGG. RECENT FINDINGS: Technologic advances offer the potential to limit volume of normal brain exposed to low doses of radiation when treating pLGG with either conformal photon or proton RT. Recent neurosurgical techniques such as laser interstitial thermal therapy offer a "dual" diagnostic and therapeutic treatment modality for pLGG in specific surgically inaccessible anatomical locations. The emergence of novel molecular diagnostic tools has enabled scientific discoveries elucidating driver alterations in mitogen-activated protein kinase (MAPK) pathway components and enhanced our understanding of the natural history (oncogenic senescence). Molecular characterization strongly supplements the clinical risk stratification (age, extent of resection, histological grade) to improve diagnostic precision and accuracy, prognostication, and can lead to the identification of patients who stand to benefit from precision medicine treatment approaches. The success of molecular targeted therapy (BRAF inhibitors and/or MEK inhibitors) in the recurrent setting has led to a gradual and yet significant paradigm shift in the treatment of pLGG. Ongoing randomized trials comparing targeted therapy to standard of care chemotherapy are anticipated to further inform the approach to upfront management of pLGG patients.

Stem-like cells drive NF1-associated MPNST functional heterogeneity and tumor progression.

NF1-associated malignant peripheral nerve sheath tumors (MPNSTs) are the major cause of mortality in neurofibromatosis. MPNSTs arise from benign peripheral nerve plexiform neurofibromas that originate in the embryonic neural crest cell lineage. Using reporter transgenes that label early neural crest lineage cells in multiple NF1 MPNST mouse models, we discover and characterize a rare MPNST cell population with stem-cell-like properties, including quiescence, that is essential for tumor initiation and relapse. Following isolation of these cells, we derive a cancer-stem-cell-specific gene expression signature that includes consensus embryonic neural crest genes and identify Nestin as a marker for the MPNST cell of origin. Combined targeting of cancer stem cells along with antimitotic chemotherapy yields effective tumor inhibition and prolongs survival. Enrichment of the cancer stem cell signature in cognate human tumors supports the generality and relevance of cancer stem cells to MPNST therapy development.

Spontaneous Regression in a Patient With Infantile Fibrosarcoma.

Infantile fibrosarcoma usually presents as a rapidly growing mass on the extremities or trunk. We describe spontaneous regression in a 5-month-old female infant with biopsy proven, molecularly confirmed, right leg infantile fibrosarcoma currently at 26 months of age with no signs of local recurrence. Previously reported cases of spontaneous regression are reviewed, suggesting a benign clinical course in some cases. Although evidence for spontaneous regression is anecdotal in this rare tumor type, physicians should weigh the risks and benefits of surgery and chemotherapy against watchful waiting.

Ovarian hyperstimulation syndrome.

Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic complication of assisted reproduction technology. The syndrome is characterized by cystic enlargement of the ovaries and a fluid shift from the intravascular to the third space due to increased capillary permeability and ovarian neoangiogenesis. Its occurrence is dependent on the administration of human chorionic gonadotrophin (hCG). ß-hCG and its analogs, estrogen, estradiol, prolactin, histamine and prostaglandins have all been implicated in OHSS but now it is increasingly better understood that the vasoactivesubstances such as interleukins, tumor necrosis factor-α, endothelin-1, and vascular endothelial growth factor (VEGF) secreted by the ovaries have been implicated in increasing vascular permeability. Enlargement of the ovaries causes abdominal pain, nausea and vomiting. Leakage of fluid from follicles, increased capillary permeability leading to third spacing (due to the release of vasoactive substances), or frank rupture of follicles can all cause ascites. Due to leakage of fluid through the impaired blood vessels both within and outside the ovary there is massive fluid-shift from the intra-vescular bed to the third compartment results in intravascular hypovolemia with concomitant development of edema, ascites, hydrothorax and/or hydropericardium. Low-dose gonadotrophin protocols have been implemented to reduce the risks of fertility treatment in polycystic ovary syndrome patients. Prophylactic albumin administration may interrupt the development of OHSS by increasing the plasma oncotic pressure and binding mediators of ovarian origin. OHSS is significantly lower in an antagonist protocol than in an agonist protocol. Cabergoline inhibits partially the VEGF receptor 2 phosphorylation levels and associated vascular permeability without affecting luteal angiogenesis reduces the 'early' (within the first 9 days after hCG) onset of OHSS. To prevent thrombosis, subcutaneous heparin 5000-7500 U/d is begun on the first day of admission. These patients need a hospital ward where the clinical picture is well understood and the personnel have expertise in its treatment and follow-up. Admission to an intensive care unit is necessary when critical OHSS develops.

Luteinizing hormone and its dilemma in ovulation induction.

Concept of a 'therapeutic window' of luteinizing hormone (LH) for successful conception in assisted reproductive technology and ovulation induction has been reviewed in this literature. The separate but complementary roles of follicle stimulating hormone and LH in stimulating folliculogenesis and ovulation are well established. Levels under which low LH concentrations may be equally or suboptimally needed for oocyte quality and subsequent embryonic development competence has been reviewed along with the data related to the high levels of LH promoting follicular atresia.