Cases reported "Hamartoma"

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1/9. Hamartomas of the internal auditory canal: report of two cases.

    OBJECTIVE AND IMPORTANCE: To highlight the clinical, radiological, and surgical findings and therapeutic options for this rare entity, which may mimic a purely intrameatal vestibular schwannoma, and to define the particular aspects of preoperative differential diagnosis and surgical management. CLINICAL PRESENTATION: Two patients presented with clinical findings typical of vestibular schwannomas, i.e., tinnitus, hearing loss of 30 dB, and an intrameatal contrast-enhancing lesion on magnetic resonance imaging studies. TECHNIQUE: The lesions were exposed via a suboccipital transmeatal approach, and tumor infiltration of the cochlear and/or facial cranial nerves was identified. In view of the unclear intraoperative histology, surgical management was based on criteria of cranial nerve function. In Patient 1, after nerve decompression by subtotal tumor removal, preserved auditory brainstem responses and facial nerve electromyography indicated functional nerve preservation and facilitated the decision for partial resection. In Patient 2, minimal tumor dissection resulted in complete loss of auditory brainstem response without reversibility. Therefore, a radical tumor removal was performed that sacrificed the cochlear but preserved the facial nerve. CONCLUSION: Symptoms and signs of internal auditory canal hamartomas are congruent with other typical pathological lesions of the internal auditory canal and cerebellopontine angle. Accurate preoperative diagnosis by radiological means is not possible, but careful evaluation of the different signal intensities on magnetic resonance imaging studies may indicate this rare pathological condition. Intraoperative surgical findings of tumor infiltration of the faciocochlear cranial nerve complex may support simple observation. In view of the nonneoplastic characteristic of these lesions, a more conservative approach is justified. The decision should be based on the functional status of the cranial nerves, for which reliable electrophysiological monitoring is indispensable.
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2/9. Glioneural hamartoma of the VIIIth nerve.

    Hamartomas of the cerebellopontine angle or internal auditory canal are very rare and only four cases have been reported. We report an unusual case of a glioneural hamartoma of the VIIIth nerve with clinical, radiological and audiometric similarity with vestibular schwannoma.
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3/9. Congenital neural hamartoma ("fascicular schwannoma"). A light microscopic, immunohistochemical, and ultrastructural study.

    A previously undescribed form of a congenital neural hamartoma composed entirely of schwann cells in a fascicular pattern was found on the leg of a male infant. The lesion was thought to be an unusual variant of plexiform Schwannoma or a newly recognized unencapsulated form of Schwannoma. On light microscopic examination, the lesion, which measured 5 x 4 cm when it was surgically removed when the infant was 7 months old, showed an unencapsulated dermal mass composed of fascicles of spindle cells with frequent Verocay body-like structures. The intervening stroma was collagenous and contained an increased number of mast cells. Special stains did not demonstrate any axons in the tumor. There was a strongly positive immunohistochemical reaction for S-100 protein and collagen type iv in the spindle cells. These cells were weakly or focally positive for Leu-7 and vimentin, and completely negative for neural filaments, neuron-specific enolase, glial fibrillary acidic protein, epithelial membrane antigen, desmin, and muscle-specific actin. On electron microscopic examination, the spindle cells were found to be surrounded by basal lamina and showed frequent cytoplasmic invagination filled with collagen bundles. No unmyelinated nerve fibers were identified.
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4/9. Distribution and immunoreactivity of cerebral micro-hamartomas in bilateral acoustic neurofibromatosis (neurofibromatosis 2).

    Bilateral acoustic neurofibromatosis (neurofibromatosis 2, NF2) accounts for less than 10% of all cases of neurofibromatosis and manifests itself with bilateral acoustic schwannomas, multiple schwannomas of spinal nerve roots, meningiomas, glial tumors and hamartomatous CNS lesions. We have observed dysplastic foci of immature neuroectodermal cells in the cerebral cortex and basal ganglia of six patients afflicted with neurofibromatosis 2, ranging from occasional clusters of immature, dysplastic cells to numerous, confluent lesions. These cells, although often polymorphic and multinuclear did not show mitotic activity or a tendency for neoplastic transformation. To determine the histogenesis of these foci, extensive immunocytochemical reactions were carried out with antibodies to a variety of glial, neuronal and non-neural cell lineages. With the exception of S-100 protein, no immunoreactivity was detectable. S-100 was consistently expressed in these foci, irrespective of their size, location, and degree of polymorphism. On the basis of cytological appearance, distribution and immunoreactivity we tentatively designate these foci as glial micro-hamartomas. Although we did not systematically analyze the CNS of patients with von Recklinghausen neurofibromatosis (neurofibromatosis 1, NF1), the present study strongly suggests that these micro-hamartomas constitute a morphological hallmark of bilateral acoustic neurofibromatosis (NF2).
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5/9. neurofibromatosis 2 in the pediatric age group.

    Bilateral acoustic neurofibromatosis or neurofibromatosis 2 (NF2) is an autosomal dominant disease predisposing to the formation of multiple tumors in the central and peripheral nervous system. Vestibular schwannomas (VSs) are considered to be the hallmark of the disease, but other tumors and ocular findings occur as well. In patients that do not carry the NF2 mutation, VSs usually occur in the fifth or sixth decade of life. VSs in patients with NF2 are often bilateral and become symptomatic in the third or fourth decade of life. In order to define the early manifestations of NF2, we examined nine children who either had one parent with NF2 or had multiple skin or spinal tumors suggestive of NF2. In addition to neurological, dermatological, and ocular examinations, all patients were studied by gadolinium-enhanced magnetic resonance imaging of the brain and spine. None of the children exhibited symptoms or signs due to VSs. However, VSs were detected during the neuroradiological work-up in six children. Seven children developed symptoms or signs due to skin or spinal tumors. Slit lamp examination detected cataracts in four patients as young as 10 years of age. The diagnosis of NF2 in the pediatric age group requires a high degree of suspicion and should be considered in children with multiple central nervous system or skin tumors without cafe-au-lait spots or Lisch nodules. Because VSs are unlikely to produce the signs seen at the time of admission, careful examination of the skin and eyes is necessary and should be followed by gadolinium-enhanced magnetic resonance imaging of the brain and spine. First-degree relatives need to be examined as well.
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6/9. cerebellopontine angle glioneuronal hamartoma.

    Roughly 90% of cerebellopontine angle tumors are acoustic neuromas. Other prevalent lesions include meningiomas and epidermoid tumors; additional lesions are rare. We describe a patient with a neuroglial hamartomatous mass of the internal auditory canal who was thought to have a schwannoma preoperatively. In this case, the hamartomatous tissue containing neuroectodermal elements may have become separated from the developing neuraxis during neural migration. Hamartomas should be considered when masses are discovered originating from eighth nerve branches other than the superior vestibular nerve and when magnetic resonance signal characteristics vary from the T1 enhancement typically seen with schwannomas and meningiomas.
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7/9. Cutaneous malignant melanotic neurocristic tumors arising in neurocristic hamartomas. A melanocytic tumor morphologically and biologically distinct from common melanoma.

    Cutaneous neurocristic hamartomas (CNH) are pigmented lesions of neural crest origin that involve the skin and superficial soft tissue. They consist of a complex proliferation of nevomelanocytes, schwann cells, and pigmented dendritic and spindled cells. Malignancies can arise within the lesions, but few studies have dealt with this issue. We studied seven cases of CNH in which malignancy supervened. They included four congenital and three acquired lesions that involved the head and neck (five cases) or back (two cases) in patients aged from 11 to 67 (mean, 32) years. Malignant tumors developed 15 to 67 (mean, 32) years after identification of the pigmented lesion in the congenital CNH and after 1 to 6 (mean 3.5) years in the acquired CNH. The malignant tumors had a deep intradermal or subcutaneous origin and lacked a junctional component. Most were circumscribed, multinodular, melanin-containing tumors composed of bland, small, rounded to spindled cells, focally displaying a trabecular or nested growth pattern. Nuclear palisading and perivascular pseudorosettes were present in several tumors. In two examples, the neoplasm consisted predominantly of large pleomorphic epithelioid cells. Tumors contained immunoreactive S-100 protein (all of seven cases), a melanoma-associated antigen (HMB-45)( five of six cases, neuron-specific enolase (five of seven cases) and vimentin (six of six cases). The four patients with congenital lesions tended to have multiple recurrences and died of disease after 2 to 20 (mean, 9) years, three with metastases, one with direct invasion of the posterior fossa. The three patients with acquired lesions are alive after 1 to 5 years two with persistent disease. In contrast to common melanomas, these tumors have a propensity to recur as bulky nodules and to metastasize after many years or decades. Because these tumors exhibit melanocytic differentiation and arise in hamartomatous lesions composed of neural crest derivatives, we have designated them cutaneous malignant melanotic neurocristic tumors.
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keywords = schwann cell, schwann
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8/9. blindness, deafness, quadriparesis, and a retinal malformation: the ravages of neurofibromatosis 2.

    Advances in molecular biology have established that the diseases once collectively referred to as neurofibromatosis are actually genetically distinct and clinically heterogenous conditions. This realization has led to separate definitions for neurofibromatosis (NF) type 1 and 2. Although ophthalmologic manifestations of NF1 have long been recognized, the distinguishing ocular features of NF2 have only recently received attention. We describe an inferior retinopapillary malformation with an overlying glial hamartoma in a deaf, quadriparetic patient with NF2. Magnetic resonance (MR) imaging initially showed bilateral vestibular schwannomas and a large cervical ependymoma. Over six years of follow-up, the patient developed multiple intracranial meningiomas.
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9/9. The ocular presentation of neurofibromatosis 2.

    neurofibromatosis 2 (NF2) is an inherited disorder characterised primarily by bilateral vestibular schwannomas and other central nervous system tumours. Individuals with NF2 also have early onset cortical and posterior subcapsular or capsular cataract and other ocular abnormalities, such as retinal hamartomas. Although their diagnostic significance is rarely appreciated, the ocular manifestations are often the first sign of disease. We describe 5 cases that illustrate the diverse ocular manifestations of NF2.
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