John J. Kepes

Presidential address: the histopathology of meningiomas. A reflection of origins and expected behavior?

Meningiomas and their principal cells of origin, the arachnoidal “cap” cells are unique in their morphology with multiple and sometimes seemingly contradictory features related to their origins and basic character. Some meningiomas express mesenchymal features either in histologic pattern (fibroblastic, lipo-myxochondro-osteoblastic differentiation), participation in other disease processes, e.g. taking part in the formation of rheumatoid nodules, or in storage phenomena shared with other mesenchymal cells of the body. At the same time they may display epithelial features, such as well-formed desmosomes ultrastructurally, papillary formations and intracellular lumina in cells that stain positively for various cell markers usually considered to characterize epithelial cells. Histologic similarities of meningiomas to various gliomas, schwannomas, neuroblastomas, fibrous histiocytomas, myxomas, chordomas, metastatic carcinomas, and in the cases of meningiomas with marked inflammatory infiltrates, to benign or malignant lymphoproliferative disorders involving the meninges may pose serious diagnostic problems. The localization and resectability of meningiomas are important factors related to long-term prognosis. Of the histologic features hemangiopericytomatous pattern, papillary formations, high cellularity (focal or diffuse) and invasion of the brain appear to correlate with potentially aggressive behavior, whereas cytologically aneuploidia, large number of mitoses, prominent nucleoli and cell necrosis suggest a guarded prognosis. However, some meningiomas with no detectable histologic features of malignancy may nevertheless metastasize to distant sites.

Cystic lesions associated with intracranial meningiomas.

Three unusual cases of large, peritumoral cystic lesions associated with intracranial meningiomas are reported. In each case, the cyst caused difficulty in the interpretation of the computed tomogram when the latter was considered as a diagnostic test by itself, but the composite information obtained from the clinical history, cerebral angiography, and a radionuclide brain scan led to the correct preoperative diagnosis. The cyst was extrinsic to the tumor and contained xanthochromic fluid with a high protein content. The cyst wall consisted of brain parenchyma that showed glial cell proliferation (confirmed by the presence of glial fibrillary acidic protein by immunoperoxidase staining).

The Fine Structure of Hyaline Inclusions (Pseudopsammoma Bodies) in Meningiomas

Hyaline inclusions of a meningothelial meningioma were examined under the electron microscope. These eosinophilic, PAS-positive proteinaceous structures, which under the light microscope are seen in both extra- and intracellular location, were found by electron microscopy to consist of granular masses surrounded by cell membranes with microvilli. The intracellular bodies were also surrounded by similar microvilli in a space within the cells. Such spaces, variously known as intracellular ductules and neolumen formation, have been previously described in mammary cancer, bronchiolar carcinoma and pleural mesotheliomas, among others, and have been, in the latter instances, regarded as signs of secretory differentiation. Thus, hyaline inclusions of meningiomas are different from truly intracellular hyaline bodies of neoplastic astrocytes (found by Rubinstein and Herman to be bodies within autophagic vacuoles) and may be regarded as a possible factor in ultrastructural differential diagnosis between meningiomas and gliomas.

A case of thalamic aphasia with postmortem verification

This study discusses a case of aphasia after dominant thalamic lesion, a hemorrhagic infarction. Unlike other such cases, both repeated standardized assessment and postmortem verification were available. The patient was assessed at 3 weeks and again at 9 weeks postonset. The aphasia demonstrated the syndrome common to dominant thalamic hemorrhage: fluent but paraphasic output sometimes deteriorating to jargon, comprehension less impaired than this type of output usually indicates, and the least impairment in repetition. As sometimes reported in previous cases, semantic paraphasias were more common than phonemic paraphasias. The lesion was located in the dorsal aspect of the lateral nucleus, but it extended into the pulvinar, including the anterior superior lateral aspect which has been implicated in language by previous studies. Thus, data from this case are consistent with an involvement of the dominant pulvinar in language and suggest that this role involves the semantic aspects of language.

Astrocytomas: old and newly recognized variants, their spectrum of morphology and antigen expression

The relationship between the morphology of astrocytomas and their prognosis is complex, with the localization of the tumour, the predominant cell type and the degree of anaplasia all playing an important part in determining the patients future. Since many astrocytomas have a diversity of patterns, small needle biopsies taken from just one or a few areas may fail to elucidate the principal features of a given tumour. In addition to the astrocytoma subtypes listed in the WHOs International Histological Classification of brain tumours, new entities have been observed in the last few years. These include lipidized forms, such as the relatively benign pleomorphic xanthoastrocytoma and the highly malignant lipidized glioblastoma. Neoplastic astrocytes are capable of forming basal laminae and of phagocytosis, and often contain alpha-1-antitrypsin, features that may lead to confusing them with histiocytes. They may be arranged in a whorled pattern imitating meningiomas, their myxoid intercellular stroma may assume the morphology of cartilage and closely packed tumour cells in epithelioid astrocytomas come close to imitate metastatic carcinoma. Some astrocytomas contain cells indistinguishable from those of granular cell tumours of other tissues. The presence of reactive lymphocytes in astrocytomas and reactive astrocytes in malignant lymphomas can be the source of confusion between those two kinds of neoplasms.

Cerebellar medulloblastoma in a 73-year-old woman.

A case of a 73-year-old woman with cerebellar medulloblastoma is described. The patient presented with the classical symptoms and signs of a medulloblastoma, and radiological findings were also consistent with this entity. Nevertheless, because of the patients advanced age, the possibilities of metastatic tumor involving the cerebellum or a primary cerebellar lymphoma were considered before operation. Pathological examination of the operative specimen showed a classical medulloblastoma with occasional areas of early neuroblastic differentiation. Immunoperoxidase strains for neurofilaments were of help in confirming the neurogenic origin of the neoplastic cells. Although medulloblastomas in adults are not rare, onset after the age of 50 is exceptional, with only two cases on record in patients 65 or older. The present patient seems to be the oldest individual with a cerebellar medulloblastoma thus far reported.

Meningioma with pseudoglandular pattern. A case report

A falx meningioma in an 11-year-old girl had a hemangiopericytomatous and papillary pattern, but the dominant histologic feature was a pseudoglandular arrangement of the tumor cells, closely imitating an adenocarcinoma. The gland-like spaces resulted mainly from dissolution of the centers of cell nests, and to a lesser extent from the fusion of papillary processes. The tumor recurred locally five years after surgery and maintained its pseudoglandular pattern. Recognition of the existence of a pseudoglandular variant of meningiomas can prevent the mistaken diagnosis of a metastatic adenocarcinoma and other similar tumors.

Intracellular Mucoid Changes in Tumor Cells of Meningiomas: A Manifestation of Polyvinylpyrrolidone (PVP) Effect on Tissues with Mesenchymal Characteristics

In two cases of meningiomas in Taiwanese patients, extensive intracellular mucoid changes were found within tumor cells, together with deposits of polyvinyl-pyrrolidone (PVP) granules. Both patients had in the past received intravenous PVP as a plasma expander. Recipients of PVP have previously been reported to develop a form of PVP thesaurismosis with concomitant mucoid changes in the cells storing this substance. Such changes, as a rule, were limited to cells of mesenchymal origin. By storing PVP granules and undergoing mucoid changes as a result, meningioma tumor cells behave as cells with mesenchymal characteristics.

Cellular whorls in brain tumors other than meningiomas

Cellular whorls with or without secondary calcification are generally regarded as reliable diagnostic criteria in the differential diagnosis of meningiomas. They may however occasionally occur in other primary and metastatic brain tumors. Five cases (metastatic laryngeal carcinoma, metastatic mammary carcinoma, metastatic melanoma, medulloblastoma, and giant cell glioblastoma) are presented to illustrate this phenomenon occurring in non‐meningothelial brain tumors.

Penetration of neuronal perikarya by capillaries in chronic limbic encephalitis

In a case of chronic limbic encephalitis in a 5 7-year-old man many neurons in the pyramidal cell layer of the hippocampus bilaterally were penetrated by ingrowing capillaries. All gradations from slight to moderate indentation of the cell membranes to complete incorporation of the capillaries in the neuronal perikarya were observed. The penetrating capillaries retained their basement membranes. Because of the chronic inflammation there was extensive fibrous gliosis in Ammons horn. This apparently had an immobilizing effect on these neurons; it is postulated that proliferating capillaries of the active inflammatory process were unable to displace local neurons and instead grew against and through their perikarya.