Computed tomography in the diagnosis of intracranial neoplasms in children

[Primary pediatric tumours of the central nervous system. Anatomopathological study of 623 cases]

Tumours of central nervous system (CNS) represent the second most frequent malignancy in children under 15 years of age but are the commonest cause of death. The authors present the epidemiologic and histopathologic analysis of 623 primary tumours of CNS occurring during the period 1990 to 1996 in paediatric patients. In this period 3318 biopsies of CNS were analyzed. In this total were included 623 paediatric tumours (18 7%). The age of patients ranged from 5 months to 15 years, 325 tumours occurred in males and 298 in females. The majority affected the posterior fossa. The majority of paediatric neoplasias were of glial origin (n = 277). The most frequent tumours were: astrocytoma (27.9%), medulloblastoma (9.95%), craniopharyngioma (5.93%), ependymoma (4.97%) and glioblastoma (3.37%).

Neuroimaging

Nonenhanced CT scan remains the most valuable and available neuroimaging study available in the ED. Nonenhanced CT scans are excellent for identifying acute hemorrhage, mass lesions, hydrocephalus, and cerebral edema. It is of limited value in identifying old blood, small abscesses and tumors, arteriovenous malformations, and aneurysms; in these cases, either enhancement of the CT or MR imaging may be preferable. The role of MR imaging is evolving and is becoming a neuroimaging modality more easily available to the emergency physician. When available, it is the preferred neuroimaging study for ischemic infarcts, lacunar infarcts, and encephalitis.

Changes in proliferating cell nuclear antigen expression in glioblastoma multiforme cells along a stereotactic biopsy trajectory

Proliferating cell nuclear antigen, an auxiliary protein of deoxyribonucleic acid polymerase-delta, has been shown to be a reliable marker of nuclear deoxyribonucleic acid synthetic activity. We applied a monoclonal antibody to proliferating cell nuclear antigen to a series of serial stereotactic biopsies from patients with glioblastoma multiforme and found the proliferative activity to vary relative to biopsy location within or surrounding the solid tissue component of the tumor. Twenty-seven trajectories in 26 patients were analyzed, each consisting of two to five sequential 10 x 1.5 mm core biopsies (mean = 3). The proliferative index (PI) was greatest in those cells located at the solid tumor-infiltrated parenchyma interface. PI values were significantly lower in those biopsy cores located proximal (within infiltrated parenchyma) and distal (within solid tumor tissue) to the solid tumor-infiltrated parenchyma interface (median PI values, proximal to distal: 0.38, 0.66, 5.45 solid tumor-infiltrated parenchyma interface], 0.39, 0.09%). The mean PI values were significantly lower in neoplastic cells samples from regions of peripheral hypodensity on computed tomographic scans compared with those sampled from contrast-enhancing regions (0.9 and 3.91%, respectively). There was no significant difference in the mean PI values of neoplastic cells sampled from regions of contrast enhancement or central hypodensity (3.91 and 4.31%, respectively).

Lipoma of the corpus callosum in a neonate: sonographic evaluation

Lipomas of the corpus callosum are benign neoplasms which are rarely diagnosed in pediatric patients. In infants they are congenital lesions consisting of collections of adipose tissue; their etiology is unclear. We describe a case of callosal lipoma discovered by sonography in a 2-day-old neonate.

Posterior cranial fossa tumours in childhood

We reviewed clinical and CT findings in 133 posterior cranial fossa tumours in children. All had histological diagnosis, apart from 20 cases of brain stem glioma. The majority were intra-axial tumours, including 53 medulloblastomas (40%), 31 cerebellar astrocytomas (23%), 28 brain stem gliomas (21%), 14 ependymomas (11%), and single cases of ganglioglioma, haemangioblastoma and teratoma. Extra-axial tumours formed only 3%, including 2 chordomas and 2 schwannomas. The clinical data and CT findings are reviewed. Cerebellar astrocytoma involved the sexes equally, while medulloblastoma, brain stem glioma, and ependymoma were more common in males. Most cerebellar astrocytomas were in the midline, and presumably arose from the vermis. The frequency of calcification was similar to that in previous reports, being highest in ependymoma (69%), followed my medulloblastoma (29%), cerebellar astrocytoma (17%), and brain stem glioma (8%).

Clinical and CT correlates in the diagnosis of intracranial tumours

The correlation between clinical and CT findings in cerebral tumours was prospectively studied in 1191 consecutive referrals for cerebral CT. CT revealed a mass lesion in 51 cases (4.3%): 32 neoplasms, five haematomas and one abscess. The diagnostic specificity of CT for neoplasmic tumours was 86% (32 of 37). The clinical suspicion of a cerebral neoplasm was correct in 25 cases (78%) and the clinical localisatory hypothesis was correct in 20 cases (63%) of the neoplasms. A cerebral tumour was found in 5% (11 out of 226) of patients investigated for their first seizure and in 1% (two of 207) investigated for headache without clinical signs.

Stereotactic-endoscopic procedures on processes of the cranial midline

The term "midline tumour" is defined partly from the topographic and from the pathogenetic point of view. Problems of modern imagegenerating procedures in establishing the diagnosis of cerebral midline lesions are described. The role of stereotactic diagnostic and therapeutic interventions is emphasized. Stereotactic brain tumour biopsy, installation of shunts and reservoirs under visual control are performed. Interstitial radiotherapy is carried out for low-grade gliomas. As an important innovation, stereotactic procedures are combined with endoscopic techniques. Particular diagnostic and therapeutic difficulties of typical midline tumours such as craniopharyngeoma, germinoma, glioma and primary cerebral lymphoma as a local extension are discussed. A reasonable concept in diagnosis and therapy of cerebral midline lesions is proposed.

Radiation therapy for brain stem tumor with special reference to CT feature and prognosis correlations

Seventy-nine patients with tumors of the medulla oblongata, pons, and midbrain treated by radiation therapy between 1962 and 1987 were analyzed. According to histology obtained in 28 cases, 61% were high-grade astrocytomas and 39% were low-grade astrocytomas. The 5- and 10-year survival rates of 71 patients who completed radiotherapy were 17 and 15%, respectively. Various potential prognostic factors were analyzed, and patients with a midbrain tumor, with a low-grade tumor, and without cranial nerve paresis were found to have a better prognosis. Computed tomography (CT) was performed both before and after radiotherapy on 42 patients. The volume of the tumor estimated from the CT image was various, but the tumors could be classified into three types according to the pattern of contrast enhancement (CE). Twenty-three tumors showed no CE, 15 showed a diffuse CE, and 4 showed a ring CE. No-CE tumors were generally hypodense on plain scan and were mostly large, whereas diffuse- or ring-CE tumors were relatively small. A complete response (CR) or partial response was obtained with 77% of the no-CE tumors, 64% of the diffuse-CE tumors, and 50% of the ring-CE tumors. The CR rate was higher in the tumors with a smaller volume. The 5-year survival rates for diffuse-CE, no-CE, and ring-CE tumors were 33, 15, and 0%, respectively. The 5-year survival rate was 56% for tumors smaller than 6 cm3, 16% for tumors between 6 and 20 cm3, and 0% for tumors larger than 20 cm3. In conclusion, (a) ring-CE tumors exhibited a poor prognosis; and (b) a diffuse-CE tumor, or a small or middle-sized no-CE tumor is most likely to be controlled by conventional radiation therapy.