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Background: Pilocytic Astrocytoma (PA) is the most common pediatric brain tumors. PAs are slow-growing tumors with high survival rates. However, a distinct subgroup of tumors defined as pilomyxoid astrocytoma (PMA) presents unique histological characteristics and have more aggressive clinical course. The studies on genetics of PMA are scarce. Methods: In this study, we report one of the largest cohort of pediatric patients with pilomyxoid (PMA) and pilocytic astrocytomas (PA) in Saudi population providing a comprehensive clinical picture, retrospective analysis with long-term follow-up, genome-wide copy number changes, and clinical outcome of these pediatric tumors. We examined and compared genome-wide copy number aberrations (CNAs) and the clinical outcome of the patients with PA and PMA. Results: The median progression free survival for the whole cohort was 156 months and it was 111 months for the PMA, however, not statistically significantly different between the groups (log-rank test, P = 0.726). We have identified 41 CNAs (34 gains and 7 losses) in all tested patients. Our study yielded the previously reported KIAA1549-BRAF Fusion gene in over 88% of the tested patients (89% and 80% in PMA and PA, respectively). Besides the fusion gene, twelve patients had additional genomic CNAs. Furthermore, pathway and gene network analyses of genes in the fusion region revealed alterations in retinoic acid mediated apoptosis and MAPK signaling pathways and key hub genes that may potentially be involved in tumor growth and progression, including BRAF, LUC7L2, MKRN1, RICTOR, TP53, HIPK2, HNF4A, POU5F, and SOX4. Conclusion: Our study is the first report of a large cohort of patients with PMA and PA in the Saudi population that provides detailed clinical features, genomic copy number changes, and outcome of these pediatric tumors and may help better diagnosis and characterization of PMA.
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BACKGROUND: Cerebellar pilocytic astrocytoma (PCA) is one of the few CNS tumors that can be cured with gross-total removal (GTR). In this series, we had 39 patients diagnosed with cerebellar PCA, 27 patients (70%) had GTR, and mean follow-up period was 62 months with no tumor recurrence. OBJECTIVE: To assess the long-term outcome of childhood cerebellar PCA treated at our institute during the period 2000-2020 and to highlight our surgical protocol. METHODOLOGY: Retrospective review of all patients under 18 years of age who were diagnosed with cerebellar PCA and had surgical excision between 2000 and 2020 at the Medical City of King Saud University. RESULTS: The study included 39 patients: 17 males and 22 females, the mean age was 8.4 years. Radiologically, the tumor was solid in eight patients, cystic in 15 patients, and mixed components were found in 16 patients. The lesion was located in the right cerebellar hemisphere in 12 patients, left cerebellar hemisphere in five patients, and midline 22 patients. The tumor size ranged from 2 to 7 cm in its greatest diameter, it was <5 cm in 13 patients and >5 cm in 26 patients. Thirty-one patients had preoperative hydrocephalus. GTR of the tumor was achieved in 27 patients and subtotal resection (STR) was done in 12 patients, 18 patients required permanent ventriculoperitoneal (V-P) shunt, and five patients had postoperative radiotherapy. Postoperative complications included infection in two patients, cerebellar mutism in two patients, and significant neurologic disability in four patients. The duration of follow-up ranged from 0 to 240 months (mean follow-up period: 62.0 months). The outcome at 10 years was good in 30 patients, fair in four patients, poor in four patients, and one patient died. Recurrence was documented in nine patients, seven of them had GTR and two had STR. CONCLUSION: GTR, if achievable, is curative for childhood cerebellar PCA. Many posterior fossa surgical complications could be avoided with watertight dural closure. Although new dural substitutes are available we prefer using autologous grafts (pericranium). It is easy to harvest pericranial graft from the external ventricular drain (EVD) site. The insertion of EVD synchronously with GTR of the tumor and gradual weaning of EVD could avoid the insertion of V-P shunt.
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BACKGROUND: Surgical treatment for elderly patients with thoracolumbar (TL) kyphosis and spinal cord (SC) compression presents significant challenges due to compression location, the amount of deformity, and patient's medical status might not permit full correction of the deformity. In this series, we present a surgical approach that provides adequate decompression without the risks associated with a pedicle subtraction osteotomy/posterior vertebral column resection or an anterior corpectomy. METHODS: Three patients presented with TL kyphosis and progressive neurologic symptoms. All had acute weakness; none were ambulatory. SC was compressed over the apex of kyphosis, and for some, there was spinal stenosis at the proximal junction of the TL spine. The surgical technique involved unilateral resection of the pars, pedicles, the posterior one-third of the lateral wall of the vertebral body, decancellation of the impinging kyphus, and finally resection of the posterior vertebral body wall compressing the SC followed by instrumentation and fusion two levels above and below the fused segments. RESULTS: All patients survived the procedure and left the hospital after 10-22 days. Estimated blood loss was 653 ml. No deep infections occurred. One patient developed acute tubular necrosis but recovered fully. The other two showed improvement of one Frankel grade and were independent in the final follow-up. One patient developed acute tubular necrosis but recovered fully yet his neurologic status was unchaged. The other two showed improvement of one Frankel grade and were independent in the final follow-up. CONCLUSION: The procedure described presents a compromise that fits the more elderly patient that might not be able to tolerate major deformity correction and at the same time provides similar results in the short and medium term to more extensive procedures.
