Martin G. Netsky

Epidermoid tumors: Review of the literature

Reports of epidermoid tumors from 1965 through 1986 were reviewed with emphasis on new and unusual findings. Clinical data considered were rapid onset, rare symptoms, size and rate of growth, and complications. Uncommon locations included multiple sites in one patient and the anterior fontanelle. The radiologic data from computed tomography were the main contributors to diagnosis. An immunohistochemical test disclosed that cells of craniopharyngiomas are keratin-positive. Histologically benign epidermoids can behave as highly malignant tumors, and can become carcinomatous. Postoperative results for benign tumors were often excellent. Evidence was presented of the close relation among epidermoid and dermoid tumor, craniopharyngioma, ameloblastoma (adamantinoma), Rathkes cleft cyst, and aural cholesteatoma.

The Brain of the Planarian as the Ancestor of the Human Brain

The planarian is the simplest living animal having a body plan of bilateral symmetry and cephalization. The brain of these free-living flatworms is a bilobed structure with a cortex of nerve cells and a core of nerve fibres including some that decussate to form commissures. Special sensory input from chemoreceptors, photoreceptor cells of primitive eyes, and tactile receptors are integrated to provide motor responses of the entire body, and local reflexes. Many morphological, electrophysiological, and pharmacological features of planarian neurons, as well as synaptic organization, are reminiscent of the vertebrate brain. Multipolar neurons and dendritic spines are rare in higher invertebrates, but are found in the planarian. Several neurotransmitter substances identified in the human brain also occur in the planarian nervous system. The planarian evolved before the divergence of the phylogenetic line leading to vertebrates. This simple worm therefore is suggested as a living example of the early evolution of the vertebrate brain. An extraordinary plasticity and regenerative capacity, and sensitivity to neurotoxins, provide unique opportunities for studying the reorganization of the nervous system after injury. Study of this simple organism may also contribute to a better understanding of the evolution of the human nervous system.

Mesenchymal differentiation in trigeminal neurilemmoma

An unusual neurilemmoma of the trigeminal nerve in a 31‐year‐old woman is described. The neoplasm was roentgenographically calcified and contained various types of mesenchymal tissue, including a cavernous angioma, cartilage, bone, and adipose tissue. Angioma in combination with neurilemmoma occurs more frequently than other forms of mesenchymal tissue. Lipoma is an uncommon component of neoplasms affecting the cranial nerves. Cartilage and bone are rarely encountered in benign intracranial neurilemmomas. The histogenesis of this combined neoplasm is discussed in relation to the ectomesenchymal properties of the neural crest.

Intracanalicular Neurilemmomas Clinicopathologic Study

Twenty-five patients with intracanalicular neurilemmomas were studied, the largest series yet reported. The tumors were most frequent in men by a ratio of 2:1, occurred more often on the left acoustic nerve, were generally associated with long duration of symptoms, and were equally distributed in the third to fifth decades, but the prevalence slightly increased in the sixth and seventh decades. A shorter length of illness occurred in younger persons as well as most patients with von Recklinghausens disease. The length of illness ranged from six months to 35 years. Symptoms generally were limited to the auditory nerve except in three instances of involvement of the facial nerve. These three cases were the only ones with preoperative facial palsy. Posterior fossa myelogram was the most useful diagnostic aid. The rate of growth in one patient was estimated to be 1 to 2 mm per year by serial study of myelograms, but the growth rate is probably variable. CT scans were not useful in detecting small tumors. Histologically, most tumors less than 1 cm in diameter were primarily composed of Antoni type A tissue. Vascular malformations were found within the tumor in three cases. Altered blood vessels are the mechanism whereby characteristic changes occur in the cerebrospinal fluid (CSF). Small tumors generally lack blood vessels, hence are less often associated with abnormal CSF.

Combined angioma and glioma (angioglioma)

Ten patients in whom tissue proliferation akin to angioglioma occurred within the brain are described; seven of the lesions were supratentorial and three infratentorial. Only 31 accepted instances of such neoplasms have been found in the literature. The combined lesions usually become symptomatic in the second and third decades. In all 10 cases, the angiomatous part of the combined tumors showed characteristic vascular malformation such as severe hyalinization, tortuosity, and some were even calcified. The number of abnormal blood vessels were excessive in all examples. The glial portion consisted of either astrocytoma, oligodendroglioma, or mixtures of these gliomas. Dedifferentiation of the neuroglia combined with neoplastic endothelial proliferation indicates the true neoplastic nature rather than reactive gliosis associated with a vascular anomaly.

Hypothesis: Phylogenetic Diseases of the Nervous System

A few human diseases may be viewed from a phylogenetic perspective. Some metabolic or degenerative diseases selectively affect recently evolved or exclusively mammalian structures of the brain and spare the older structures. Examples include Krabbes leukodystrophy, olivopontocerebellar atrophy, Friedreichs ataxia, Picks disease, and Lebers optic atrophy. Some pathologic conditions in man are similar to normal anatomy in other species, although the mechanisms may differ. Congenital muscle fiber-type disproportion in rodents, Dandy-Walker cyst in birds, and agenesis of the corpus callosum in marsupials are representative of this category. Loss of basal dendritic spines from pyramidal cells in Picks disease is reminiscent of certain large neurons normally found in the cortex of reptiles. Changes in metabolism in the evolution of mammals in general and of man in particular may explain some aspects of phylogenetic diseases. Some potential examples are the shift from predominantly phospholipids to galactolipids in myelin composition as mammals evolved, and the greater toxicity of cyanide and other poisons of oxidative metabolism in mammals than in other vertebrates because of less reliance on anaerobic metabolism as an alternative energy source.

Combined occurrence of mucin-producing ependymoma and neuroepithelial (colloid) cysts.

A three-month-old girl had a generalized convulsion which later recurred intermittently. She eventually suffered a right hemiparesis and died at two years of age. An ependymoma, probably congenital, with papillary formation and an excessive production of mucin was present, both above and below the tentorium. Part of the supratentorial tumor filled the left lateral and third ventricles. The choroid plexus of the left lateral ventricle contained multiple small neuroepithelial (colloid) cysts. Although both these lesions of neuroepithelial origin have been encountered throughout the neuraxis, their combined occurrence is rare. Multiple neuroepithelial cysts should be differentiated from cystic ependymoma and follicular adenoma of the choroid plexus. Neuroepithelial cells, both normal and abnormal may produce mucin. A few instances of intracranial neuroepithelial (colloid) cysts together with other lesions have been reported. The associated disorders include hydranencephaly (28); xanthogranuloma (xanthoma) in the third ventricle (35); frontoethmoidal meningoencephalocele, acqueductal stenosis, obstructive hydrocephalus, and microphthalmia (34) and congenital vascular anomalies of the brain (31). The subject of the present report is the combined occurrence of an intracranial ependymoma producing excessive mucin, and multiple neuroepithelial cysts of the choroid plexus of one lateral ventricle.

Developmental anomalies of the horns of the lateral ventricles.

The illustration of the cerebral ventricles devised by Retzius (1) has been used almost universally in textbooks of anatomy, radiology and neurology. This single picture showed a fairly symmetrical ventricular system. As a result of its wide use, the frequent asymmetry between the two sides of the normal ventricle and the differences from one brain to another are little appreciated. This report of the macroscopic and microscopic appearance of the horns of the lateral ventricles deals with several anatomic variations which help account for the differences in the ventricles.

Prevalence of cerebral hemorrhage and thrombosis in Japan: Study of the major causes of death

Abstract The view has long been held that cerebrovascular disease and especially cerebral hemorrhage is the major killer in Japan, causing about 25% of all deaths, and that these diseases are more frequent in the North. This impression is based on information from death certificates. Data are presented to show a large diagnostic error in certification of cerebrovascular diseases, and especially of cerebral hemorrhage. Comparison of these data with those from autopsies done throughout Japan reveal major discrepancies: malignant neoplasms are the major killer, vascular lesions of the CNS constitute 4.5% of deaths, cerebral thrombosis exceeds cerebral hemorrhage, and predilection for the North is not found. These necropsy data, however, have many deficits, notably factors of selection, age and sex distribution, quality of reports, and small number in relation to total deaths. Autopsies performed by the Atomic Bomb Casualty Commission have greater validity. They are free from biases of selection for hospitalization and clinical interest. The group studied has age and sex characteristics of the mortality group in Japan. The quality of data is relatively high, and material is available for review. The ABCC findings also reveal that malignant neoplasms are the major cause of death, being 30.4%. Vascular lesions of the CNS were the fifth most frequent cause of death, and may be lower. Cerebral thrombosis slightly exceeded hemorrhage in the ABCC series. Clinical data further substantiate the concept that the rate of fatal cerebrovascular disease in Japan is similar to that in the United States. It is suggested that the high rate of cerebrovascular disease, and especially of cerebral hemorrhage, in Japan is an artefact of diagnosis and method of recording.