Cellular schwannoma. A clinicopathologic, DNA flow cytometric, and proliferation marker study of 70 patients.

BACKGROUND: A clinicopathologic study of 70 cases of cellular schwannoma was performed to assess their distribution, response to therapy, and rate of recurrence relative to modern prognostic indicators. METHODS: Seventy-one cellular schwannomas from 70 patients were retrieved from the files of the Mayo Clinic Tissue Registry. The significance of mitotic index, proliferative marker staining (proliferating cell nuclear antigen and MIB1), immunochemical p53 expression, and DNA ploidy were assessed relative to tumor behavior, particularly recurrence. All parameters were subject to statistical analysis (Student's t test). RESULTS: Cellular schwannomas represented 4.6% of benign peripheral nerve tumors operated on at the Mayo Clinic. In 15% of the cases, an initial diagnosis of malignancy had been made. The median patient age was 47.7 years (range, 15-80 years) and the female-to-male ratio was 1.6:1. The principle tumor locations were the para- and intraspinal regions, including the sacrum (64%), extremities (25%), and intracranial space (8%). All tumors consisted primarily of hypercellular, compact, Antoni A tissue. Mitoses (< or = 4/10 hPF]) were observed in 71% of the cases. Foci of necrosis were noted in 11% of cases. Ultrastructural studies and immunohistochemistry clearly demonstrated features of schwannian differentiation. Surgery was the treatment in all cases. Excision was intralesional to gross total in the majority; total resection with wide margins was undertaken in three tumors, each of which had initially been considered malignant. Follow-up in 47 patients (67%) ranged from 1 to 29 years (mean, 7.7 years) and revealed recurrences in 11 patients (23.4%): no patient experienced metastasis or died of tumor. Although no correlation existed between recurrence and DNA ploidy, percent S-phase determinations, proliferation marker (PCNA, MIB1) staining, or the frequency of p53 immunoreactivity, a statistically significant correlation (P < 0.001) was observed, however, between recurrence and mitotic indices. CONCLUSION: Proliferation indices, as defined by immunochemical analysis, are not useful predictors of recurrence in cellular schwannoma. In lesions not completely resected, tumor recurrence is significantly correlated with mitotic count. The significant overall frequency of recurrence in this series is attributable to a high proportion of intraspinal and intracranial tumors. Our study confirms the benign nature of cellular schwannoma and underscores the necessity of distinguishing them from malignant peripheral nerve sheath tumors, lesions that often require adjuvant therapy.

Intracranial parenchymal schwannoma. A clinicopathological and neuroimaging study of nine cases.

The clinical, radiological, and pathological features of nine cases of intracranial parenchymal schwannoma are described. The clinical course in four patients 23 years of age or younger mirrored the indolent nature of this neoplasm. Imaging studies included computerized tomography in eight patients and magnetic resonance imaging in three. The lesions were well demarcated with only mild surrounding edema. Five tumors were deep within the temporoparieto-occipital region, three were in the cerebellum, and one lay peripherally in the parietal lobe. Over two-thirds of the nine tumors were either cystic (five) or contained areas of cystic degeneration (two). One lesion was frankly hemorrhagic. A variety of imaging characteristics and contrast enhancement patterns were observed, including those of a cyst with a mural nodule and peripheral enhancement. Of the four solid neoplasms, two enhanced homogeneously while the other two demonstrated heterogeneous enhancement. Six tumors were resected totally. The follow-up period ranging from 2 months to 2 years has shown no recurrences. Microscopically, immunohistochemically, and ultrastructurally, the tumors were indistinguishable from peripheral schwannomas. A possible mechanism underlying the histogenesis of these rare lesions is discussed. The importance of recognizing this tumor is stressed, particularly in younger patients, given its benign nature, radiological resemblance to other tumors such as pilocytic astrocytoma, and favorable response to resection.

Dermoid cyst mimicking hematoma in the posterior fossa.

Intracranial dermoid cysts are usually reported to be associated with long lasting or waxing-waning symptoms. Computer tomography (CT) scans usually depict such neoplasms as well-defined areas of low density. This report is about a case of a dermoid cyst, the acute clinical features and CT hyperdensity of which mimicked a hematoma in the posterior fossa. The association of acute onset with CT hyperdensity makes this case of dermoid cyst very unusual.

Central neurocytoma. A clinico-pathologic study of five cases.

Five cases of central neurocytomas are described. The tumors occurred in relatively young patients (range 14 to 43 years; mean age, 27) with no predilection for sex. All the lesions were located in the anterior portion of the lateral ventricles or in the third ventricle, involving the septum pellicidum or the fornix. Histologically, they were composed of uniform cells with round nuclei and clear cytoplasm resembling oligodendrogliomas or, to a lesser extent, ependymomas. In 4 tumors, protein cell nuclear antigen immunostaining showed a low cell proliferation rate. All cases were positive for neuron-specific enolase. Four of the 5 cases were strongly immunoreactive for synaptophysin. The immunohistochemical data were consistent with neuronal differentiation. Resection was subtotal in 4 cases and total in one. Postoperative radiotherapy was given in only one case. The follow-up revealed a good prognosis: 4 patients were alive and had a long survival (from 2 to 8 years). Only one patient died after 14 months for causes unrelated to the neoplasm. The authors emphasize the importance of immunohistochemistry to recognize this benign intraventricular tumor.

Late malignant recurrence of childhood cerebellar astrocytoma.

Juvenile pilocytic astrocytoma of the cerebellum has a benign course and a good prognosis. We report a case of juvenile cerebellar astrocytoma in a 6-year-old girl that underwent surgical resection of the tumor and had two recurrences, 13 and 35 years after first removal. After surgery the patient did not receive any radiation therapy. The last relapse showed histological features of an anaplastic astrocytoma. Six months later the patient died with a diffuse leptomeningeal dissemination. Late malignant transformation of a benign cerebellar astrocytoma is very rare and it is thought to be favored by postsurgical irradiation. The possible pathogenetic mechanisms of this evolution are discussed. This case and the few others reported in the literature emphasize the risk of an unpredictable outcome with the low-grade cerebellar astrocytomas of childhood.

Different distribution of thiaminpyrophosphatase activity in neuronal and glial cell enriched fractions from human and rat brain: an isoelectric focusing investigation.

Enriched fractions of neuronal and glial cells from rat and human (autoptical specimens of frontal cortex) brains were assayed for thiaminpyrophosphatase (TPPase) activity by isoelectric focusing (IEF). Glial and neuronal fractions yielded about 0.16 and 0.03 g/g of wet tissue respectively. Purity was estimated to be 85-90%. The isolated fractions were homogenized in the presence of 1% Triton X-100, and IEF was carried out on thin layer polyacrylamide gel in a pH range of 3.5-9.5, using Ampholine PAG plates. TPPase activity of the protein bands was assayed by laser-densitometry, after incubation with thiaminpyrophosphate in an appropriate buffer and PbS staining. IEF analysis showed that TPPase activity was present almost exclusively in the neuronal fraction (at levels 16-fold higher than those found in the glial fraction). After IEF, TPPase activity was present in 10 distinct protein bands with different isoelectric points. These preliminary data suggest that TPPase may be involved in the neuronal activity of rat and human brain.

[Neuropathology of the acquired immunodeficiency syndrome]. / Neuropatologia della sindrome da immunodeficienza acquisita.

Neuropathology of acquired immunodeficiency syndrome. The Central Nervous System (CNS) has been examined at autopsy in 60 patients who died of AIDS in a 6-year period in our hospital. Most of the patients were intravenous drug abusers, the mean age was of 34 years, with a high prevalence of males. Neurologic symptoms were present in 62% of patients, while histologic lesions have been observed in 51 cases (85%). Opportunistic infections were found in 27 patients, the commonest being T. gondii (12) and Cytomegalovirus (7); Progressive Multifocal Leukoencephalopathy was observed in 2 cases. HIV-associated lesions included 21 cases of Multifocal Giant Cell Encephalitis (MGCE), 15 of Progressive Diffuse Leukoencephalopathy (PDL) and 7 cases of Vacuolar Myelopathy. Primary CNS lymphoma was noted in 8 patients and secondary deposits were observed in 3 cases. Simultaneous CNS lesions by more than one pathogen were frequently encountered. The main pathogenetic mechanisms for characterization of all the lesions and their relationship with clinical features of the disease are discussed. It is supposed that MGCE and PDL represent two different patterns of HIV-encephalopathy.

Adenomyoepithelioma of the breast with a distinctive type of apocrine adenosis.

A newly recognized type of dimorphic carcinoma of breast, distinct from adenoid cystic carcinoma, is described. It is characterized by a predominantly solid, clear cell myoepithelial proliferation, with centrally situated glandular lumina lined by apocrine cells. All cases arose in association with a distinctive type of atypical apocrine adenosis which has to be distinguished from microglandular adenosis and from tubular carcinoma. The biological behaviour of the tumour remains to be ascertained on the basis of longer follow-up, but it appears to have only limited malignant potential.

Blue nevus of the endocervix. A study of five cases.

The pathologic and immunohistochemical features of 5 cases of blue nevus of the endocervix are presented: 4 of them were studied ultrastructurally. The lesions were incidentaly discovered at microscopic examination and showed pigmented dendritic cells in the cervical stroma. Immunocytochemical examination showed all cases to be positive for S-100 protein. Ultrastructurally they contained melanosomes, were surrounded by a basement membrane, and displayed occasional desmosome-like devices. Histogenesis is discussed, and support for a schwannian origin is presented.

A clinicopathological study of seven cases of primary high-grade malignant non-Hodgkin's lymphoma of the central nervous system.

Seven cases of primary non-Hodgkin's lymphomas of the central nervous system are described. Six cases were diagnosed after pathologic examination of surgical material; in one case, a patient with acquired immunodeficiency syndrome, the diagnosis was made at autopsy. The mean age of the patients was 52 years. The lesions were supratentorial in all cases, and unifocal in 6: the autopsy case had multicentric lesions. The cytologic examination of the cerebrospinal fluid was performed in 3 cases and was negative. The most common histologic type was immunoblastic lymphoma. The mean postoperative survival time was 12 months; in 2 cases, surgery combined with radiotherapy prolonged the survival for more than 2 years. Leptomeningeal involvement was considered to indicate a poor prognosis.

Neonatal haemophilus aphrophilus meningitis.

Case report of a neonatal meningitis due to Haemophilus influenzae. The treatment with ampicillin was ineffective because of insensitivity. This case demonstrates the importance of a proper bacteriological identification in order to avoid ineffective or delayed treatment.