WHO classification of tumors of the nervous system: preview of the upcoming 5th edition

SummaryIdentification of the underlying genetic and epigenetic alterations in an increasing number of tumors of the nervous system is contributing to a more clinically relevant classification. In the following article, the 7 cIMPACT-NOW publications, which adumbrate the upcoming 5th edition of the WHO Classification of Tumours of the Central Nervous Sytem are summarized.

Choroid Plexus Papilloma with Dandy Walker Variant: Co-existence or Association- A Case Report

Choroid plexus tumors are rare intracranial tumors which account for 0.4-0.6% of all brain tumors. Choroid plexus tumors represent a spectrum of neoplasms derived from papillary epithelium of normal choroid plexus, including well-differentiated papilloma (WHO grade I), intermediate form as atypical Choroid Plexus Papilloma (WHO grade II) and highly aggressive choroid plexus carcinomas (WHO grade III). Though rare, it is responsible for the communicating hydrocephalus in children due to overproduction of cerebrospinal fluid. Due to advances in molecular biology and better understanding of the tumorigenesis of choroid plexus papilloma, now it is established that several genetic syndromes and central nervous sytem abnormalities are associated with this tumor. Here, we reported a case of a 10 months old child who presented with sudden deterioration of consciousness level and after thorough evaluation, diagnosed as a case of Choroid Plexus Papilloma with Dandy Walker Variant. Till date, this is the first reported case of the association/ co-existence of such two conditions which needs further evaluation. Bangladesh Med J. 2017 May; 46 (2): 61-65

Evidence that histamine is a neurotransmitter in an insect extraocular photoreceptor pathway

The pair of vasopressin-like immunoreactive (VPLI) neurones of the locust Locusta migratoria have cell bodies in the suboesophageal ganglion and extensive arborization throughout the central nervous sytem. The activity of the VPLI neurone is regulated by a spontaneously active excitatory descending interneurone (DI) that is, in turn, inhibited by an uncharacterised extraocular photoreceptor (EOP) system located in the brain. Light directed at the brain results in inhibition of DI activity, which thereby deprives the VPLI neurone of its major synaptic input. We present evidence that histamine plays an important role in the EOP­DI­VPLI pathway. Histamine mimics the EOP-mediated inhibition of the DI, and the H2-specific histamine antagonists cimetidine and ranitidine block its inhibitory action. Histamine application to various areas of the brain localises the area where histaminergic inhibition occurs; this region is confined to the medial protocerebrum. At least six bilaterally paired histamine-like immunoreactive neurones send axonal projections into this area. Depolarisation of the brain region containing the soma of these neurones with high-K+ saline deactivates the VPLI neurone through the removal of the DI excitatory synaptic input.

Neuron-Specific Enolase

The clinical value of neuron-specific enolase as a marker in small cell lung cancer, neuroblastoma, melanoma and seminoma has been reviewed The role of serum and cerebrospinal NSE in benign and malignant disease of the central nervous sytem is discussed.

Catecholamine-secreting malignant schwannoma in a patient with multiple intracranial aneurysms

✓ A case is reported of malignant schwannomatosis (malignant transformation of von Recklinghausen's disease) with catecholamine production in a patient with multiple intracranial aneurysms. The patient had a history of episodic hypertension and elevated levels of catecholamines in the serum and 24-hour urinary excretion. Postmortem examination revealed diffuse central nervous sytem (CNS) dissemination of the tumor from the thoracolumbar spinal malignant schwannoma. A high concentration of catecholamines was demonstrated in the tumor tissue, and histochemical and electron microscopy studies suggested the presence of catecholamines in the cytoplasm of some of the tumor cells. This patient's clinical and radiological features, including severe headache, vomiting, stiff neck, ptosis of the eye ipsilateral to the internal carotid-posterior communicating artery aneurysms, and local arterial narrowing, mimicked those of subarachnoid hemorrhage from a ruptured aneurysm. However, the clinical picture was caused by diffuse CNS dissemination of the tumor, another primary malignant schwannoma of the oculomotor nerve, and intimal fibrous thickening of the arterial wall.