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Objective: To clarify the role of immunohistochemistry in the diagnosis of psammomatoid ossifying fibroma (PSOF), conventional cemento-ossifying fibroma (COF), and psammomatous meningioma (PM) of the craniofacial skeleton., Study Design: The histology and immunohistochemistry of 4 PSOFs, 6 COFs, and 7 PMs was studied. Antibodies included EMA, cytokeratins, smooth muscle actin (SMA), desmin, vimentin, CD34, CD10, S-100 protein, and glial fibrillary acidic protein (GFAP)., Results: All PSOFs showed multiple round ossicles homogeneously distributed within a fibroblastic stroma. Psammomatous meningiomas had meningothelial features. All tumors, except 1 COF, were positive for EMA. All of them expressed vimentin, and none showed cytokeratins. Staining for SMA and S-100 protein was variable. CD10 was positive in all cases except 2 meningiomas. CD34 and GFAP stained only 1 case of meningioma each., Conclusions: The diagnosis of PSOF should rest on histologic features. An incorrect diagnosis of meningioma based on the expression of EMA should be avoided.

A meningioma with a significant component of granular cells is described in the left ocular orbit of a 5-year-old male Golden retriever dog that presented with exophthalmos. The neoplastic mass surrounded the optic nerve. Microscopically, the tumour was characterized by nests of large, round to polygonal cells, variable in size, with eccentric nuclei and abundant eosinophilic cytoplasm, containing PAS-positive granules. In focal areas, cells were smaller and occasionally formed whorl-like structures. Immunohistochemical analysis revealed that neoplastic cells reacted positively for vimentin and, with less intensity, for neuron specific enolase and S-100, whereas they were negative for glial fibrillary acidic protein and cytokeratins. Metastatic growths, formed by similar cells, were seen in the lung and heart.

Malignant meningiomas (MMs) are aggressive intracranial neoplasms with a 75% 5-year recurrence rate. Verotoxin 1 (VT1) is an Escherichia coli toxin, which has recently been shown to have anti-neoplastic action by targeting the globotriosylceramide (Gb(3)) glycolipid on tumor cells and tumor neovasculature. To investigate the potential use of VT1 as a clinical agent for MM, we initially tested 16 meningiomas for Gb(3) expression. Nine of 11 MMs (82%), but only one of five benign meningiomas (20%), were positive for Gb(3). An orthotopic xenograft model was used to test the efficacy of VT1 treatment for MM. We first demonstrated that Gb(3) was highly expressed by the MM cell line, IOMM-Lee, and that this cell line was highly sensitive to VT1 treatment in vitro. A single intratumoral injection of VT1 significantly improved survival in nude mice harboring intracranial tumours (P<.0001). Factor-eight immunostaining of tumours harvested from VT1-treated animals revealed a marked reduction in the tumour microvascular density. In addition, the tumors of VT1-treated animals displayed increased apoptosis by TUNEL analysis and showed a significant decrease in cell proliferation, as determined by MIB-5 immunostaining. VT1 treatment of MM is effective in our orthotopic xenograft model, and warrants further exploration as a potential treatment for these highly anaplastic and aggressive neoplasms.

A 23-month-old, male, Labrador retriever dog with a history of slowly progressive right-sided atrophy of the masticatory muscles was submitted for necropsy. A highly invasive neoplasm which destroyed adjacent soft tissues including the right trigeminal nerve was found in the right side of the cranial cavity. Metastases to the liver were also present. Microscopical features of the neoplasm were compatible with those of rhabdomyosarcoma, embryonal type. This diagnosis was confirmed by immunohistochemical demonstration of desmin and muscle actin within tumour cells. In human patients, rhabdomyosarcoma is the most common soft tissue sarcoma of childhood and adolescence. Parameningeal rhabdomyosarcomas are well-known topographic variants that are often non-amenable to complete surgical resection and therefore carry a more guarded prognosis. Juvenile parameningeal rhabdomyosarcoma resulting in denervation atrophy of the muscles of mastication has not been reported previously in dogs. Rhabdomyosarcoma should be included in the differential diagnosis of neoplastic conditions in the head and neck region of juvenile dogs presented with cranial nerve palsies or other neurological deficits suggestive of meningeal or central nervous system invasion., (Copyright Elsevier Science Ltd. All rights reserved.)

We investigated the expression of c-myc and c-sis/PDGF mRNA and protein products in 20 cases of meningiomas of various grades: 10 benign, 5 atypical and 5 anaplastic meningiomas. All cases of atypical and anaplastic meningiomas were positive for c-myc protein and mRNA by immunohistochemistry and in situ hybridisation, respectively, while all 10 benign meningiomas were negative for c-myc immunostaining, with only one benign tumour positive for c-myc mRNA. Expression of PDGF-BB protein and c-sis mRNA were seen in more than 80% of the meningioma cases and was not restricted to the histological grades of meningiomas. Semiquantitative analysis showed that the frequency of c-myc immunopositive cells positively correlated with Ki-67 proliferative indices. Our findings suggest that c-myc, but not c-sis/PDGF, has some concern to the malignancy of meningiomas.

Primary brain tumours and pregnancy rarely occur together; meningioma and pregnancy is rarer still. We describe a 30-yr-old woman in the 25th week of pregnancy who underwent surgery in the sitting position for a large cerebellopontine angle meningioma that was compressing and displacing the pons and medulla. The surgical procedure and postoperative period were uneventful. This case demonstrates that when absolutely necessary, anaesthesia and neurosurgery for posterior fossa lesions can be successful during the second trimester of pregnancy. Furthermore, if indicated and if the operating team is experienced, the operation can be performed safely with the patient in the classical sitting position. It is emphasized that continuous and attentive monitoring of the mother and fetus are essential.

A subcutaneously transplantable meningeal tumour (MM-KMY) was derived from a spontaneous malignant meningioma which developed in the cerebellar meninges of a female F344 rat. MM-KMY was subjected to 25 serial passages in syngeneic male and female rats. The transplants grew in 8 weeks into a nodule with an average diameter of 5.7 cm and average weight of 125.2 g. MM-KMY possessed large cysts containing fluid and necrotic tissue. Metastases frequently occurred in the lungs of MM-KMY-bearing rats. Histologically, both the original tumour and MM-KMY consisted of round to fusiform neoplastic cells of varying size, with nuclear pleomorphism. Mitotic figures occurred frequently. MM-KMY cells were positive for vimentin. Ultrastructurally, the cells showed desmosome-like structures, interdigitating processes and cytoplasmic intermediate filaments, suggesting an arachnoid cell origin. Abnormal accumulations of hyaline droplets in renal tubular epithelial cells were frequently observed in MM-KMY-bearing rats, suggesting overload of low molecular proteins in the renal tubules. The droplets gave a faint immunoreaction for lysozyme. The relation between the appearance of renal tubular hyaline droplets and the growth of MM-KMY remains to be determined. MM-KMY may prove useful for studying the biological behaviour and morphogenesis of meningeal tumours.

Polypeptides, characterized by their ability to confer a transformed phenotype on an untransformed indicator cell have been isolated directly from surgical specimens of intracranial meningioma by using an acid/ethanol extraction procedure. Transforming activity in meningeal cells was based on the ability to induce NRK 49F rat kidney fibroblasts to form colonies in soft agar. This polypeptide was separated by gel filtration into two fragments of 15 and 40 kilodalton (kDa) molecular weight. Among other cases of brain neoplasms, one case of glioblastoma multiforme had moderate TGF-beta activity, but medulloblastoma and neurinoma had no activity. Purified TGF-beta also stimulated DNA synthesis in primary cultured meningioma cells, but no effect was seen in U 251MG human glioma cells. While the physiological function of TGF-beta is still ill-defined and the molecular character of its receptor has not been analyzed, intracranial meningiomas are noted to have TGF-beta-like activity. TGF-beta also induces the DNA synthesis of cultured meningioma cells. From these results, TGF-beta would be considered one of the growth promoting factors in meningioma.