Fenestrated blood vessels in craniopharyngioma

The role of inflammation in the genesis of the cystic component of craniopharyngiomas

BACKGROUND

Craniopharyngioma accounts for 5-10% of childhood tumors and, despite of the benign histological features, its clinical course can be malignant because of critical anatomical relationships with neural and vascular structures and the possible morbidity associated to resection. Only a few studies have addressed the molecular characterization of the cyst fluid so far and the mechanisms of action of intracystic agents are not clearly understood yet.

METHODS

The acidic soluble proteins contained in the cystic fluid of six patients with cystic craniopharyngioma, three of them treated with intratumoral interferon-α, were analyzed. A high performance liquid chromatography electrospray ionization mass spectrometry analysis was performed.

FINDINGS

The antimicrobial peptides α-defensins 1-3 relevant for innate immunity were detected in the cystic fluid before the intratumoral treatment. Amount of peptides significantly decreased in cystic fluid during pharmacological treatment.

INTERPRETATION

Detection of α-defensins 1-3 excludes that cyst fluid formation can derive from disruption of blood-brain barrier and suggests the involvement of innate immune response in pathology of craniopharyngioma cyst formation. The reduction of α-defensins could derive both from direct antitumoral effect of interferon-α on squamous epithelial cells of craniopharyngioma cyst and from its immuno-modulatory effects on the recruitment of cells of innate immune systems. Interestingly, the clinical patient outcome well correlates with the gradual reduction of α-defensins 1-3 amount. Additional studies will be necessary to establish the role of these molecules in the pathogenesis of craniopharyngioma, and further investigations will be necessary to confirm the efficacy of the antitumoral activity of interferon-α.

A histopathological study of craniopharyngioma with special reference to its stroma and surrounding tissue

The numerous pathology reports on craniopharyngioma describe the classical features of squamous epithelium and keratin. Relatively little attention has been paid to its stroma and the surrounding tissue. We focused our observation on these two areas in a retrospective study of craniopharyngiomas in 36 operative cases and 5 autopsy cases. The tumor interdigitated with the brain and pituitary gland. At the interface, the brain was markedly gliotic with Rosenthal fibers simulating pilocytic astrocytoma. The tumor stroma had reactive changes and commonly showed cyst formation and calcification.

Fenestrated capillaries in subarachnoid space in the caudal spinal cord of the premature rat: an electron microscopic observation

The fine structure of the conus medullaris of the spinal cord and surrounding structures were studied in postnatal developing rats, with special attention being paid to the vasculature. The most striking finding was the presence of fenestrae in the capillary endothelium of the subarachnoid space. These structures were not obvious in adult rats. The fenestrated capillaries may influence fluid dynamics in the subarachnoid space of the spinal cord at the level of the conus medullaris, during early stage of postnatal development.

Secretory component of cystic craniopharyngiomas: a mucino-histochemical and electron-microscopic study

Ten cases with cystic craniopharyngioma were investigated. Histologically, eight of them belonged to the adamantinomatous group and two were squamous epithelial type. Histochemical investigation revealed mucin secretion in microcysts, and electron microscopy demonstrated zymogen granules in the epithelial cells. When the protein content of the cyst fluid was analyzed by polyacrylamide-gel electrophoresis, the electrophoretic pattern and immunological properties were found to be similar to the normal human serum control. The results of the morphological study suggest that cystic craniopharyngiomas have a secretory component in addition to the classical histological structures.

Pathological changes in cystic craniopharyngiomas following intracavital 90yttrium treatment

Radiosurgery, using 90Y injected directly into the cavity of cystic craniopharyngiomas produces remarkable reduction of tumour size and diminishes cyst fluid production. The authors have studied the histology of biopsy and autopsy material obtained from seven patients presented with cystic craniopharyngiomas. Histological examination was carried out before and after 90Y silicate implantation. As an effect of 90Y irradiation, histology of samples taken from the cyst wall revealed that the lining epithelial cell layer became destroyed and the cyst wall shrunk. Large amount of collagen fibres with focal hyaline degeneration was present. Proliferation of intimal cells and subendothelial connective tissue narrowing small vessel lumina also occurred. Considering that fibrotic tissue is more susceptible to shrink, the fibrosis induced by irradiation together with destruction of the squamous epithelium and vascular changes, might explain the reduction of the cyst volume and diminished fluid secretion after 90Y treatment.

Ultrastructural study of micro-blood vessels in human brain tumors and peritumoral tissue

Ultrastructural and tracer studies have demonstrated that vasogenic edema, a serious complication of brain tumor is the result of increased permeability of tumor vessels. However, not much information is available on the alterations in the vessels in the peritumoral areas. Therefore, we studied the ultrastructural changes in the tumor micro-blood vessels (MBVs) in 20 cases of glioma and compared these with the changes in the peritumoral MBVs in 10 of these cases. The tumor MBVs showed remarkable structural changes, viz, increase in pinocytotic vesicles, large vacuoles and microvilli in the endothelial cells, varying degrees of endothelial attenuation and fenestration, an occasional partially or completely opened-up junction and some pale and edematous endothelial cells, which can adequately explain their increased permeability. The peritumoral MBVs also showed evidence of increased permeability in the form of increased pinocytotic vesicles, large vacuoles and microvilli associated with pale and edematous cytoplasm of some endothelial cells. Thickened multilayered basement membrane, absence of ensheathment of capillary basement membrane by astrocytic cell processes and widened perivascular space were observed in both tumoral and peritumoral MBVs. An interesting observation was that in the peritumoral MBVs, the pinocytotic vesicles were most conspicuously seen on the abluminal side of the endothelial cells often fused with the abluminal plasma membrane. Although a static study like this cannot indicate any definite direction of movement of fluid, we feel that the occurrence of reverse pinocytosis is a distinct possibility in the peritumoral MBVs and that it may be an important means of resorption of edema fluid.

Benign cystic lesions in the central nervous system. Light and electron microscopic observations of cyst walls

A wide variety of benign cystic lesions is known to occur in both adults and children. Recent advances in diagnostic radiology have facilitated meaningful surgical intervention in most instances. It is convenient to classify these cysts into two groups. The first group includes those that arise from defects wholly within the central nervous system. Among these are certain static lesions such as cystic cavities arising from infarcts and other destructive lesions. Some of these are observed to communicate with the subarachnoid space or ventricle. The progressive lesions in this group include arachnoid cysts, ependymal cysts, cystic hemangioblastoma, cystic cerebellar astrocytoma, and certain infectious processes. The second group is constituted by cysts resulting from the intrusion of non-nervous tissue into the neuroaxis, usually in the midline. These are expanding congenital lesions, although some become symptomatic only in the adult. Among these are teratomas, dermoid cysts, epidermoid cysts, craniopharyngiomas, Rathke's cleft cysts, and other epithelial cysts apparently derived from the upper respiratory or the intestinal tract. Colloid cysts of the III ventricle are usually considered to be neuroectodermal in origin, but certain features suggest an endodermal origin.

Ultrastructure of cerebellar capillary hemangioblastoma. VI. Concentric lamellar bodies of endoplasmic reticulum in stromal cells

Concentric lamellar bodies of endoplasmic reticulum (CLB) were found in the stromal cells of all five cases of cerebellar capillary hemangioblastoma studied ultrastructurally. CLB were often present in the stromal cells with voluminous loose cytoplasm, particularly those close to the capillaries. They were rarely seen in small stromal cells with abundant organelles and stromal cells distended by large lipid droplets. Small lipid droplets were usually present in the center or in the vicinity of CLB. Vesiculation and vacuolization of the lamellar arrays of CLB were common. Some vacuolized CLB were transformed into large, varying-shaped, multilocular bodies. Some stromal cells were markedly distended by numerous large vacuoles derived from CLB. Granulo-fibrillary material was frequently present in the vacuolized lamellae. Discharge of vacuoles into the interstitial space was observed. It is suggested that CLB is one of the characteristic ultrastructural features of the stromal cells. They may represent a special type of hyperplasia of the endoplasmic reticulum, but their functional significance is not known.

Malignant melanoma. Inflammatory mononuclear cell infiltrates in cerebral metastases during concurrent therapy with viral oncolysate

Five patients with advanced malignant melanoma, treated with viral oncolysate, had solitary central nervous system metastases that were removed surgically. Histologic examination revealed striking and significant mononuclear inflammatory cell infiltrates, consisting of a mean of 60% plasma cells and a lesser proportion of lymphocytes at the edges of the lesions, within their supporting fibrovascular trabeculae, and among the tumor cells. Comparable inflammatory changes were not found in solitary metastatic malignant melanomas removed surgically from the brains of 19 patients not treated with viral oncolysate. Similarly, multiple metastatic malignant melanomas obtained postmortem from the brains of 12 patients not treated with viral oncolysate showed minimal inflammatory responses. Ultrastructural examination of material from a single treated patient revealed morphologic abnormalities of the blood-brain barrier, changes that were perhaps conducive to infiltration of the neoplasm by inflammatory cells. The authors suggest that administration of viral oncolysate enhances the inflammatory cell response to metastatic malignant melanoma in the brain.

Experimental brain tumors and edema in rats. I. Histology and cytology of tumors

In this study an experimental intracerebral tumor has been investigated with special consideration of structures, which may be involved in edema production and/or resolution. For this purpose a cloned tumor cell line (RG1 2.2) has been injected stereotactically into the brain of BD-IX rats. The tumor has some characteristics in common with low differentiated oligodendroglioma in men. A honeycomb architecture may be seen in the center of the tumor. It is built up by rounded or elongated cells, which can be impregnated in parts. In the central area, cells exhibit a voluminous digestive apparatus, composed of dictyosomes, vesicles, and some vacuoles with a membranaceous or homogeneous content. Tumor cells in the periphery show large processes and a small digestive apparatus. The sinusoidal tumor vessels are composed of an endothelium with many vesicles but no openings.

Fenestrated blood vessels in human skeletal muscle

In a fine structural study of 32 skeletal muscle biopsies, rare examples of fenestrated blood vessels (FV) were found in three cases. In view of similar observations reported in a case of Duchenne muscular dystrophy, it is suggested that FV albeit rare may occur in skeletal muscle at least under pathologic conditions. These aberrant FV may be derived from adjacent dermis and/or epineurium which are known to contain occasional FV. Alternatively, the occurrence of fenestrae may reflect a nonspecific alteration in pre-existing continuous endothelium. The significance, if any, of their presence in skeletal muscle is unknown.

Ultrastructural changes in blood vessels of peripheral nerves in leprosy neuropathy. I. Tuberculoid and borderline-tuberculoid leprosy patients

Radial or superficial peroneal nerve biopsies of 6 patients with tuberculoid or borderline-tuberculoid leprosy and 6 control nerve biopsies were examined by electron microscopy. Endoneurial blood vessels showed histopathology in all the leprosy patients. Changes, in particular, involved the basement membrane in postcapillary venules and venules. Multilayered parellel basement membranes, with collagen and ground substance, formed a thick coat ("hyaline zone") around the vessels. It is suggested that the zone inhibits passage of nutrients and metabolites and, thus, contributes to or is the main cause of the local destruction of (unmyelinated) nerve fibres and the lack of nerve fibre regeneration observed in this type of leprosy. The perivascular zone, presumably, is produced by pericytes in response to defects in the "blood-nerve barrier" of endoneurial vessels. In granulomata of leprosy skin lesions, a perivascular zone was not present. The endothelium of endoneurial vessels, in affected nerves, generally was normal. Occasionally, however, gaps and fenestrations were seen and there were histological indications that leakage of blood plasma had occurred through the gaps and through the basement membrane of the endothelium. Occlusion of endoneurial vessels was found only in the oldest patient and the degeneration of nerve fibres generally observed thus is considered not to be caused by ischaemia. Histopathology in epi-and perineurial vessels was definitely less pronounced than in endoneurial vessels.

Craniopharyngiomas: a clinical and pathological review

Two hundred and forty-five cases of craniopharyngiomas were obtained from the files of the AFIP and reviewed statistically with reference to their gross and microscopic appearance and clinical data. The majority of the tumors were cystic and microscopically, cysts were formed by squamous epithelial maturation, by degeneration of the stellate cells at the centers of adamantinomatous nests, or by degeneration of the stroma. Transitional forms were seen between adamantinomatous and squamous epithelium and keratohyaline granules and keratin were present in some cases. Because of this overlap, differentiation between craniopharyngiomas and suprasellar epidermoid cysts often is not possible. Significantly increased acturial survival rates were associated with absence of calcification in plain skull films in adults, negative CSF examination, and tumor size under 3.0 cm.

Fine structure of intercellular junctions and blood vessels in medulloblastomas

Six medulloblastomas were studied by electron microscopy. Two features were found which seem to be constant and essential characteristics of medulloblastoma. First, cell junctions are abundant between tumor cells. These are mostly desmosome-like but other, closer junctions, were also seen. Second, the capillary endothelia contain frequent tubular bodies and other inclusions which may be related to them.

Vascular structures in brain tumors

The blood vessels within brain tumors show alterations from the normal anatomy. Some of these seem to be related to an increased capacity to transfer materials between the lumen and the parenchyma and are probably intimately connected with the edema associated with the tumor. These alterations include fenestration, widened intercellular junctions, increase in pinocytotic vesicles, and infolding of the luminal surface. Other alterations are observed but their function is not as clear. The latter include an increase in the number of tubular bodies, the appearance of tubular structures within vacuoles, tubular arrays within the nuclear envelope and rough endoplasmic reticulum, and endothelial proliferation, among others.

Some new observations in an intracranial germinoma

A case of an intracranial germinoma from the suprasellar region of a 9-year-old girl was examined in the electron microscope. The tumor consists, for the most part, of both large polygonal and small lymphocyte-like elements. Annulate lamellae are common in the epithelial cells. The small blood vessels are fenestrated, and the endothelial cells contain tubular bodies, membrane-bounded vacuoles containing dense fluid and occasional tubules, arrays of tubules within the nuclear envelope and rough endoplasmic reticulum, and a markedly irregular luminal surface. Dense, lamellated structures are present in the widened, collagen-containing perivascular spaces.

Optic nerve glioma in an 18-month-old child

An optic nerve glioma in an 18-month-old child was examined by both light and electron microscopy. The tumor revealed the characteristic features of uniform benign and fibrillary astrocytoma. Rosenthal fibers and calcium depostis were found within numerous intracellular glial processes. The above features indicated a slow-growing tumor of long duration, confirming the generally supported assumption of the congenital nature of optic nerve glioma. One unsuspected feature was the presence of fenestrated blood vessels.