Canine intracranial meningioma with rosette-like collagen deposits

A 13-year-old female Miniature Dachshund showed seizures and an intracranial mass was seen in the left temporal lobe. Three months after first surgical resection, a recurrence lesion was recognized. Histopathologically, proliferation of spindle cells with diffuse rosette-like eosinophilic deposits, which stained blue with Masson’s trichrome stain, was observed. In electron microscopy, the rosette-like deposits were consisted of bundles of minute filaments which were assumed to be collagenous fibrils. Immunohistochemically, the neoplastic cells were positive for vimentin and cytokeratin, and negative for E-cadherin, S100, glial fibrillary acidic protein (GFAP), oligodendrocyte transcription factor (Olig2), and CD204. The rosette-like collagen deposits were positive for type 4 collagen and negative for type 1 collagen. In this report, we describe histopathological features of a canine meningioma with the rosette-like collagen deposits.

Pathological and immunohistochemical features of 45 cases of feline meningioma

Meningioma is the most common primary brain tumor in cats, although there are few reports about their pathological features. To investigate the histopathological subtypes and immunohistochemical features including expression of cytokeratin and cell adhesion molecules, 45 cases of feline meningioma were examined. The mean age was 12.5 years (range 6–21 years). No statistically significant sex predilection was observed. Regarding the anatomical location of meningioma, tumors mostly developed in the cerebrum, followed by spinal cord and cerebellum, and multiple meningioma was observed in one cat. Microscopically, linear or focal mineralization was observed in 40 cases and cholesterol cleft was observed in 14 cases. Based on histopathological subtypes, there were 15 fibrous, 22 transitional, 2 meningothelial, 5 atypical, and 1 anaplastic meningiomas. These subtypes are classified into grade 1 (39 cases), grade 2 (5 cases), and grade 3 (1 case). There was no significant difference in the Ki-67 index among histological subtypes or grades. Immunohistochemically, the tumor cells were positive for cytokeratin in 5 cases (12.8%), vimentin in 17 cases (43.6%), E-cadherin in 36 cases (92.3%), β-catenin in 21 cases (53.8%), and N-cadherin in 1 case (2.6%), demonstrating the utility of E-cadherin-immunohistochemistry for the diagnosis of feline meningiomas.

Expression of E-cadherin and catenins in meningioma: Ubiquitous expression and its irrelevance to malignancy

The expression of cell adhesion molecules in 107 meningiomas was analyzed with immunohistochemical methods using antibodies to epithelial (E)-cadherin and catenins (alpha, beta and gamma). According to the provided World Health Organization (WHO) grading, 84, 18 and five cases were classified as grade I, II and III, respectively. In addition, hemangioblastoma (15 cases) and hemangiopericytoma (four cases) were also evaluated. In most meningiomas, E-cadherin, alpha- and beta-catenins were expressed along the cell membrane or inside the cytoplasm. The tumor cells constituting whorls and glandular structures of secretory type showed a strong immunoreactivity. gamma-Catenin expression tended to be weak and infrequent in fibrous meningiomas, while other types exhibited diffuse stainings. Even in meningiomas of more than grade II, the expressions of cell adhesion molecules were detected in all cases. Hemangiopericytoma was positive for alpha- and beta-catenins, and hemangioblastomas were positive for beta-catenin alone, which was distinct from the expression pattern in meningiomas. Quantitatively, there were no correlations between the histological variants, Ki-67 indexes, or grades of meningiomas and the immunoreactive scores except for gamma-catenin scores of fibrous meningiomas. The present study demonstrates that cell adhesion molecules are ubiquitously expressed in all variants of meningioma and may be involved in the tumor morphogenesis. This result suggests that the expression of cell adhesion molecules is not a reliable indicator of malignancy in meningiomas. The present study also suggests that these markers may be useful for the differential diagnosis of meningioma.

Vascular cell adhesion molecule-1 is a key adhesion molecule in melanoma cell adhesion to the leptomeninges

Leptomeningeal metastases occur in up to 8% of patients with systemic malignancies and have a poor prognosis. A better understanding of the pathophysiologic processes underlying leptomeningeal metastases is needed for more effective treatment strategies. We hypothesized that tumor cells will have to adhere to the well-vascularized leptomeninges, because the cerebrospinal fluid lacks nutrients and growth factors for efficient tumor cell proliferation. Specific receptor-ligand interactions, which are unknown until now, will mediate this adhesion process. We determined the growth characteristics of B16F-10 melanoma cells in cerebrospinal fluid. The expression levels of specific adhesion molecules on both mouse leptomeningeal cells (MLMC) and murine B16F-10 melanoma cells were measured by immunofluorescence flow cytometry. We used mAbs to determine the function of these specific adhesion molecules on B16F-10 melanoma cell adhesion to a leptomeningeal cell layer under static and (cerebrospinal fluid-like) flow conditions. B16F-10 melanoma cells did not proliferate in cerebrospinal fluid because of a lack of nutrients and growth factors. MLMC expressed low levels of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), beta1- and beta3-integrin subunits, and CD44. VCAM-1 expression on MLMC was shown to be up-regulated by TNF-alpha. Blocking VCAM-1 on the MLMC with a mAb resulted in a 60% inhibition of melanoma cell adhesion to a leptomeningeal cell layer under flow but not under static conditions. No additive inhibitory effect on melanoma cell adhesion was found by concomitant blocking of the beta1- and beta3-integrin subunits and CD44 with mAbs. Our experiments indicate that cerebrospinal fluid does not support B16F-10 melanoma cell proliferation, suggesting the need for melanoma cell adhesion to the well-vascularized leptomeninges. VCAM-1, expressed on MLMC, is an important mediator of in vitro melanoma cell adhesion under (cerebrospinal fluid-like) flow conditions.