MBCL-41. LYMPHOHEMATOPOIETIC TOXICITY IDENTIFIED IN PATIENTS WITH MEDULLOBLASTOMA RECEIVING CRANIOSPINAL IRRADIATION

BACKGROUND Medulloblastoma (MB) is the most common malignant brain tumor of childhood. MB easily disseminates through the spinal fluid. Surgery followed by radiotherapy, applied to the entire craniospinal axis (CSI), and adjuvant chemotherapy, represent the treatment of choice for patients aged ≥3 years. Since the bone marrow of the skull and vertebral column are the major hematopoietic organs, we investigated the myelosuppressive effect of irradiation treatment in patients with MB retrospectively. METHODS Medical records of newly diagnosed MB patients treated at our hospital from 2007–2019 were analyzed. Children <3 years old were excluded because they did not receive CSI to avoid potential neurotoxicity. RESULTS Medical records of 18 patients (11 males and 7 females, aged 6–26, median 11 years) were reviewed. Eight patients were stratified as high-risk disease and 10 patients with standard risk. All patients received CSI (dosage range 23.4–39.6 Gy based on disease risk) and posterior fossa boost. All patients developed lymphocytopenia (<0.5×109/L) during irradiation, and for 11 of 18 patients, lymphocytopenia (<0.2×109/L) was severe. Although 13 patients recovered from the lymphocytopenia before the initiation of chemotherapy, five patients underwent chemotherapy without recovery. Conversely, only six patients developed neutropenia (<1.0×109/L), and five of the six patients were <10 years old. CONCLUSION Although infectious episode associated with lymphocytopenia was not observed in this study, CSI treatment in children and adolescents may induce immunodeficient condition particularly in the lymphocytic system. Pediatric oncologists should pay attention to the impaired immunity of patients with MB who receive CSI.

Magnetic Resonance Imaging Profile of Chordomas - A Retrospective Evaluation from a Tertiary Institution of Eastern India

BACKGROUND Chordomas are tumours presumed to originate from the remnants of embryonic notochord. They present a diagnostic challenge as they can occur in any region within the craniospinal axis and are rare with an incidence of less than 0.1 / 100,000 per year. Imaging is required for their evaluation and magnetic resonance imaging (MRI) is the imaging modality of choice due to excellent soft tissue resolution, multiplanar imaging capabilities and precise anatomical delineation. METHODS MRI scans of 10 patients, who had proven chordomas histologically, were evaluated retrospectively in the Department of Radiodiagnosis, Bangur Institute of Neurosciences from July 2012 to June 2018. Patients without histological proof of chordomas and those lost to follow-up were not included in the study. Clinical information such as age, sex, presenting symptoms were noted. Imaging parameters assessed included tumour location, bone destruction, extraspinal soft tissue component, spinal canal and neural foramina encroachment, arterial encasement, signal intensity, morphology and enhancement pattern by MRI. All the cases were scanned in a 1.5 Tesla MRI machine. Intravenous contrast were used in all cases. RESULTS Of the 10 cases, 7 were male and 3 were female. There were 7 cases of sacrococcygeal chordomas and 3 cases of clival chordomas. The tumours appeared as multilobulated masses with bone destruction. All sacrococcygeal lesions involved more than one vertebral segment with extraspinal soft tissue component encroaching the pelvic cavity and showed cystic spaces containing hypointense septae. All 3 cases of clival chordomas showed compression of the pons and basilar artery. In one case there was compression of optic chiasma with displacement of internal carotid arteries laterally. On T1 weighted imaging, the chordomas were isointense in 4 and hypointense in 6 cases. These tumours were hyperintense in T2WI in 8 and intermediate to high in signal intensity in 2 cases. All demonstrated heterogenous enhancement on contrast with moderate enhancement in 8 patients and mild enhancement in 2 cases. CONCLUSIONS Chordomas are rare tumours that can occur anywhere in the craniospinal axis. MRI is the modality of choice for imaging of chordomas. Characteristic findings in MRI include low to intermediate signal intensity on T1w images and high signal intensity on T2w images. Sacral chordomas have T2 hyperintense cystic masses with hypointense septa. Enhancement is heterogenous ranging from mild to moderate. MRI is invaluable for a pre-operative diagnosis, delineation of tumour extent and as roadmap for surgery and radiotherapy. KEYWORDS Chordomas, Magnetic Resonance Imaging, Clivus, Sacrococcygeal

Ependymoma and Chordoma

Ependymoma and chordoma are 2 tumors that occur throughout the craniospinal axis, and for which the extent of neurosurgical resection has a key prognostic role. Both tumors have distinctive pathologic features, yet can present significant diagnostic challenges to pathologists in cases without classical histology. The molecular understanding of ependymoma has had significant advances in the past decade, with the identification of 9 molecular groups with significant prognostic and clinical implications, while a comprehensive study of chordoma further emphasized the key role of brachyury overexpression in its pathogenesis. In this review, we discuss the pathogenesis, radiology and gross pathology, histology, and molecular features of these 2 tumors, as well as active research into targeted therapies, with an emphasis on practical diagnostic challenges, and the use of immunohistochemical and molecular tests in routine diagnostic practice.

Ecchordosis physaliphora: a cautionary tale

BackgroundEcchordosis physaliphora is a congenital, benign lesion originating from notochordal remnants along the craniospinal axis, most frequently located at the level of the clivus and sacrum. Sometimes ecchordosis physaliphora is difficult to recognise and treat, with a total of twenty-six cases described in the literature.MethodsThis study reports on three cases of previously undiagnosed ecchordosis physaliphora presenting with cerebrospinal fluid rhinorrhoea and meningitis.ConclusionEndoscopic transclival or transsphenoid surgery including three-layer (fat, fascia and nasoseptal flap) reconstruction was used in all cases with complete resolution of the symptoms.

Differential patterns of metastatic dissemination across medulloblastoma subgroups

OBJECTIVEMetastatic dissemination is a major treatment challenge and cause of death in patients with medulloblastoma. However, the influence of molecular biology on the pattern of metastatic dissemination at diagnosis is not known. In this study, the authors sought to define the location, pattern, and imaging characteristics of medulloblastoma metastases across subgroups at diagnosis.METHODSA consecutive cohort of patients with metastatic medulloblastoma at The Hospital for Sick Children and the University Hospital Motol, who underwent up-front MRI of the craniospinal axis, was assembled and allocated to subgroups using NanoString limited gene–expression profiling. Radiological characteristics (including location, morphology, size, diffusion restriction, and contrast enhancement) were discerned through a retrospective review.RESULTSForty metastatic medulloblastomas were identified with up-front neuroimaging of the craniospinal axis: 5 sonic hedgehog (SHH), 16 Group 3, and 19 Group 4 metastases. Significant subgroup-specific differences were observed, particularly with respect to tumor location, size, and morphology. Group 3 metastases were most frequently laminar compared with a more nodular pattern in Group 4 (14 of 16 in Group 3 vs 8 of 19 in Group 4; p = 0.0004). Laminar metastases were not observed in patients with SHH medulloblastoma. Suprasellar metastases are highly specific to Group 4 (p = 0.016). Two of the 5 SHH cases had multifocal lesions in the cerebellum, raising the possibility that these were in fact synchronous primary tumors and not true metastases. A minority of patients with Group 4 metastases harbored metastatic deposits that did not enhance on MRI after contrast administration, often in patients whose primary tumor did not enhance.CONCLUSIONSThe location, morphology, and imaging characteristics of metastatic medulloblastoma differ across molecular subgroups, with implications for diagnosis and management. This suggests that the biology of leptomeningeal dissemination differs among medulloblastoma subgroups.

Use of Flattening Filter-Free Photon Beams in Treating Medulloblastoma: A Dosimetric Evaluation

Aim. To evaluate the dosimetric benefits of flattening filter-free (FFF) photon beams in intensity modulated radiation therapy (IMRT) and Rapid Arc (RA) over conventional CSI methods. Methods and Materials. Five patients treated with IMRT using static multileaf collimators (MLC) were randomly selected for this retrospective study. Dynamic MLC IMRT, RA, and conformal therapy (3DCRT) were iterated with the same CT data sets with and without flattening filter photons. Total dose prescribed was 28.80 Gy in 16 fractions. Dosimetric parameters such as Dmax⁡, Dmin⁡, Dmean, V95%, V107%, DHI, and CI for PTV and Dmax⁡, Dmean, V80%, V50%, V30%, and V10% for OARs were extracted from DVHs. Beam on time (BOT) for various plans was also compared. Results. FFF RA therapy (6F_RA) resulted in highly homogeneous and conformal doses throughout the craniospinal axis. 3DCRT resulted in the highest V107% (SD) 46.97±28.6, whereas flattening filter (FF) and FFF dynamic IMRT had a minimum V107%. 6F_RA and 6F_DMLC resulted in lesser doses to thyroid, eyes, esophagus, liver, lungs, and kidneys. Conclusion. FFF IMRT and FFF RA for CSI have definite dosimetric advantages over 3DCRT technique in terms of target coverage and OAR sparing. Use of FFF in IMRT resulted in 50% reduction in BOT, thereby increasing the treatment efficiency.