Ultrastructural pathology of anaplastic and grade II ependymomas reveals distinctive ciliary structures--electron microscopy redux.

Ependymoma tumors likely derive from the ependymal cells lining the CNS ventricular system. In grade II ependymomas, tumor cells resemble typical ependymocytes, while anaplastic ependymomas are poorly differentiated. We studied three grade II and one anaplastic ependymoma, focusing on the ciliary structures. To unambiguously characterize the ultrastructure and number of cilia, we performed electron microscopy serial section analysis of individual cells. Differentiated ependymomas contained large basal bodies and up to three cilia, and lacked centrioles. Anaplastic ependymoma cells showed instead two perpendicularly oriented centrioles and lacked cilia or basal bodies. These findings could contribute to understand the mechanisms of ependymoma aggressiveness.

Mesenchymal hamartoma of the liver; Clinicopathological, immunohistochemical and flow cytometric study of two cases.

Mesenchymal hamartoma (MH) is a rare liver lesion of infancy. Due to its rapid increase in size, it is often misdiagnosed clinically as a malignant tumour or as a hepatic cyst because of its cystic appearance. We present the clinicopathological, immunohistochemical and flow cytometric features of two cases, involving an 11-month-old boy and a 13-month-old girl. In both cases, the histological appearance and the immunohistochemical findings were identical. Bile ducts and blood vessels showed the expected immunohistochemical profile, whereas the mesenchymal component showed immunoreactivity not only for vimentin but also for muscular markers. Flow cytometry disclosed an aneuploid population in one case, thus favouring the interpretation of MH as a neoplastic lesion. Unlike the characteristically continuous and rapid growth of MH before or shortly after birth, these two cases showed low proliferative and apoptotic indexes and a high immunohistochemical expression of bcl-2 protein. This prompted us to hypothesize that MH might undergo a brief initial proliferative phase, but the cells would later become 'immortalized' by bcl-2 overexpression.

[Cervical lymphatic metastasis of an intracranial meningioma]. / Metastasis linfatica cervical de un meningioma intracraneal.

INTRODUCTION: Meningioma is the most common primary intracranial tumor, accounting for around a third of all primary brain tumor. In most cases, they are benign neoplasms that start in the cells of the arachnoid mater. Meningiomas are typically slow growing; however they can metastasize in 0.1% of all patients. CASE REPORT: A 45-years-old woman was admitted with a four weeks history of a painless enlarging mass in the right side of his neck and present in a MRI recurrence of the frontal meningioma surgically removed four times over the last 18 years. The patient underwent a complete removal of lesions and the microscopic observation showed an anaplastic meningioma in both (grade III of the World Health Organization). CONCLUSIONS: Metastatic meningioma is a rare cause of neck mass, but should be considered in any patient with a history of meningioma, especially if the tumor has histological features of malignant behavior. The present case demonstrates the aggressive biologic potential of an intracranial meningioma, with potential for distant spread and lymphatic invasion.

[Paediatric neurocysticercosis: two case reports]. / Neurocisticercosis pediatrica: a proposito de dos casos.

INTRODUCTION: Neurocysticercosis, caused by the larvae of Taenia solium, is the most common parasitic infection of the central nervous system in humans. Considered an endemic parasitosis in developing countries including Latin America, Asia and Africa while in Europa, the cases of neurocysticercosis are anecdotal. CASE REPORTS: We report two cases of neurocysticercosis in children of non-Spanish origin who presented with seizures, with the initial diagnosis of brain tumors both were treated with surgery; later, to be the diagnosis of neurocisticercosis antiparasitic therapy was administered. CONCLUSIONS: Neurocysticercosis can be a potential cause of epilepsy even in non-endemic countries. Some cases may be difficult to diagnose and they can be confused with other intracranial lesions. Clinicians should be aware of this condition given increasing incidence in Spain and neurocysticercosis should be always be considered in the differential diagnosis particularly in patients from Latin America and Africa.

[Primary cranial vault lymphoma]. / Linfoma primario de la calota craneal.

INTRODUCTION: Primary bone lymphomas account for 3-7% of all malignant bone tumours and less than 2% of lymphomas in adults. Having the cranial vault as their primary location is very infrequent. CASE REPORT: A 59-year-old female who presented a painful tumour on the cranial vault which, following radical surgical removal, was found to be an ALK-negative primary large-cell lymphoma. CONCLUSIONS: After reviewing the literature we believe that this is the first case of cranial vault lymphoma in which the translocation of the ALK protein-producing gene has been studied.

Telomerase expression and proliferative activity suggest a stem cell role for thyroid solid cell nests.

Solid cell nests of the human thyroid gland are composed of main cells and C cells. In order to investigate the putative stem cell nature of the role for solid cell nests, we evaluated the histological features, and the immunohistochemical expression of p63, bcl-2, telomerase catalytic subunit, and two proliferative markers (Ki-67 and minichromosome maintenance protein 2), in a series of 24 cases of solid cell nests. Proliferative indices were determined in (a) solid cell nests, (b) thyroid follicular cells in the vicinity of solid cell nests within a low-power field, and (c) distant thyroid tissue, at a distance of at least three low-power fields from solid cell nests. In 15 cases of solid cell nests (62.5%), mixed follicles were observed; papillary formations were observed in four cases (16.6%), and ciliated cells were observed in the lining of microcysts associated with two cases (8.3%). Salivary gland-type tissue, cartilage islands, adipose and fibrous tissues, and small nerves were also associated with some cases of solid cell nests. We observed that the main cells of the solid cell nests express consistently telomerase, although at lower levels than p63, and show strong cytoplasmic immunoreactivity for bcl-2, which is associated with an increased differentiation potential. We also observed that despite their relative low proliferative index, main cells of the solid cell nests display higher proliferation than follicular cells in the vicinity and follicular cells in more distant thyroid tissue. We conclude that main cells of the solid cell nests apparently harbor the minimal properties of a stem cell phenotype (capacity for both self-renewal, conferred by telomerase activity, and differentiation to one or more than one type of specialized cells, given by the high expression of p63 and bcl-2) and may thus represent a pool of stem cells of the adult thyroid.