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Intracranial intravascular papillary endothelial hyperplasia (IPEH), also referred to as Masson’s tumor, is a condition that rarely occurs in the nervous system. IPEH most frequently occurs extracranially in the skin of the face, skull, neck, and trunk and can easily be mistaken clinically, radiologically, and histologically for angiosarcoma, organizing hematoma, or other vascular malformations. IPEH accounts for roughly 2% of all vascular tumors and is extremely rare intracranially, with only 23 reported cases compared with more than 300 cases of IPEH occurring in the skin and subcutaneous tissue. To date, it has never been reported to occur in the pineal region. The authors report the case of a patient with an IPEH in the pineal region who underwent complex resection and experienced reversal of neurological symptoms.

Object The aim of this study was to describe the similarity of configuration between the arachnoid complex in the posterior half of the incisural space and the Liliequist membrane. Methods Microsurgical dissection and anatomical observation were performed in 20 formalin-fixed adult cadaver heads. The origin, distribution, and configuration of the arachnoid membranes and their relationships with the vascular structures in the posterior half of the incisural space were examined. Results The posterior perimesencephalic membrane and the cerebellar precentral membrane have a common origin at the tentorial edge and form an arachnoid complex strikingly resembling an inverted Liliequist membrane. Asymmetry between sides is not uncommon. If the cerebellar precentral membrane is hypoplastic on one side or both, the well-developed quadrigeminal membrane plays a prominent part in partitioning the subarachnoid space in the posterior half of the incisural space. Conclusions The arachnoid complex in the posterior half of the incisural space can be regarded as an inverted Liliequist membrane. This concept can help neurosurgeons to gain better understanding of the surgical anatomy at the level of the tentorial incisura.

Object The infratentorial supracerebellar approach to the pineal region presents special challenges during patient positioning. The head must be flexed and the body positioned to allow an operative trajectory under the straight sinus. Image guidance is not useful during positioning because registration and navigation take place after the head is fixed in its final position. Therefore, a reliable method of positioning based on external, easily identifiable landmarks to estimate the surgical trajectory along the straight sinus toward the pineal region is needed. Based on observation, the authors hypothesized that a line between 2 palpable external landmarks, the inion and the bregma, often approximates the surgical trajectory along the straight sinus. They tested this hypothesis by quantifying the relationship between the straight sinus and the bregma, and describe a method for estimating the working angle during patient positioning. Methods The midsagittal, Gd-enhanced, T1-weighted MR images of 102 patients were analyzed. Demographic data and the presence or absence of tentorial pathological entities was recorded. The slant of the straight sinus was classified as common, high, or low, based on a previously described classification system. A line along the bottom of the straight sinus (that is, the straight-sinus line) was extended superiorly to its intersection with the calvaria, and the distance from this intersection point to the bregma was measured. Results The intersection point of the straight-sinus line and the calvaria was on average 2 ± 8.2 mm (these values are expressed as the mean ± SD throughout) anterior to the bregma (range 19.9 mm anterior to 19.1 mm posterior). The distance from the intersection point to the bregma was not statistically significantly different in younger or older patients, or in patients with or without tumors involving the pineal region. In patients with a low slant of the straight sinus, the intersection point was 5.3 ± 6.3 mm anterior to the bregma, whereas in patients with a high slant of the straight sinus, the intersection point was 0.21 ± 9.1 mm posterior to the bregma (p = 0.015). Conclusions The straight-sinus line, which defines the working angle for the supracerebellar infratentorial approach, intersects the calvaria very close to the bregma in the majority of patients. Therefore, ideal patient positioning can be achieved by flexing the patient's head to optimize the working angle defined by an imaginary line connecting the torcula (inion) to the bregma.

✓ A unique case of a meningeal melanocytoma located in the pineal region is presented. This 48-year-old man presented with a round pineal region tumor that caused triventricular hydrocephalus and exhibited slow clinical progression. During surgery a black encapsulated tumor was found and totally removed. On histopathological examination, the tumor proved to be a meningeal melanocytoma. In this report cell culture data are presented and the relevant literature is reviewed. The problems of histopathological diagnosis and management of patients with melanocytomas are also discussed.

✓ Immature teratomas arising within the central neuraxis are rare neoplasms. These tumors contain diverse cell lineages that retain an embryonal character and display phenotypic differentiation attributed to the three classic germ layers. The clinical management of these lesions is unclear, due in part to their low incidence and to an incomplete understanding of their natural history. Although the potential for phenotypic differentiation and cellular maturation within immature teratomas arising in the gonads is well documented, this has not been described in the intracranial tumors. In the present report, the authors describe two cases of intracranial immature teratomas, one involving the pineal region and the other involving the left frontotemporal lobes, which underwent cellular differentiation and maturation. At initial resection, the tumors from both cases were composed predominantly of primitive neuroepithelial tissue that was admixed with immature and differentiating mesenchymal and epithelial structures. No foci of germinoma, endodermal sinus, choriocarcinoma, or embryonal carcinoma tissue were present. Subsequent resections in both cases revealed an absence of immature tissue. The tumor in Case 1 contained only differentiated epithelial and mesenchymal tissue with no neuroepithelial component, whereas the tumor in Case 2 demonstrated abundant mature neuronal and glial tissue. These two cases from different intracranial sites suggest that spontaneous maturation may be a significant aspect of the natural history of intracranial immature teratomas.

✓ Ten cases of meningioma of the pineal region were histologically verified at a single institution during an 8-year period. These represented 0.3% of 3061 intracranial meningiomas, as well as 6.2% of 164 pineal tumors. Patients were predominantly women. Symptoms and signs of increased intracranial pressure were most common, whereas Parinaud's syndrome was observed in only one case. Computerized tomography (CT) was the main diagnostic test used in the present series. It usually revealed a hyperdense mass with high-intensity contrast enhancement and a calcified mass eccentrically located at the periphery, which returned to its central location postsurgically and was likely to represent a calcified pineal gland. Magnetic resonance imaging was performed in the more recent cases and confirmed the suspicion raised by CT of a meningioma with a calcified mass at its periphery. Surgery was performed using an occipital transtentorial microsurgical approach with the patient placed in the semisitting position. Gross-total tumor removal was achieved in all cases, although this required sacrifice of the vein of Galen in six patients. Venous occlusion was performed only after adequate intraoperative verification of functional occlusion and blood flow diversion from the galenic system and had no consequences in any case but one. This latter patient had an infiltrative meningioma that was removed at the expense of intraoperative sacrifice of the two internal cerebral veins, as well as unavoidable trauma to the region of the quadrigeminal plate. All the remaining patients improved postsurgery, and only one had a permanent visual field deficit as a result of the surgical approach. Pineal meningiomas represent a rare subgroup of pineal tumors that can be treated surgically with reasonably good results. Sacrifice of major basal veins may be required to achieve radical tumor removal and can be tolerated by the patient provided that functional occlusion of the galenic system, as indicated by preoperative angiography, is verified during surgery.

✓ The authors report the case of a 53-year-old woman who experienced visual hallucinations diagnosed as peduncular hallucinosis (PH). The cause of the PH was compression of the quadrigeminal plate and/or the splenium due to a meningioma originating from the falcotentorial junction (pineal meningioma). The nature of the visual hallucinations was depicted in drawings created by the patient herself. This is the first report of PH caused by a tumor located in the pineal region.

✓ The authors describe an oligodendroglioma of the pineal region in a 59-year-old woman. The patient presented with intermittent confusion, memory disturbance, and headache associated with a cystic pineal region mass demonstrated on magnetic resonance imaging. Gross-total resection was performed via a suboccipital supratentorial approach. Pathological and genetic evaluation showed the tumor to be an anaplastic oligodendroglioma. Although the spectrum of tumors arising within the region of the pineal gland is broad, to the authors’ knowledge this is the first report of an oligodendroglioma occurring in this area.

The authors report the case of a newborn presenting at birth with macrocephaly and a large pineal region hemorrhagic cyst without neurological deficit. No neurosurgical intervention was performed, and subsequent imaging studies demonstrated complete involution of the cyst.

✓ A case of papillary pineocytoma is presented. It is necessary to be aware of this unusual histological type of pineocytoma in order to make a differential diagnosis among other types of papillary tumors that arise in the pineal region.

✓ A case is presented with the acute development of a pineal region syndrome secondary to hemorrhage into a pineal cyst in a patient who was under anticoagulant therapy. Resolution of the symptoms and signs followed excision of the lesion.

I N THE treatment of tumors in the pineal region, radiotherapy is often used following some shunting operation because the pinealoma, the most common type of pineal tumor, is highly sensitive to irradiation. Although several statistical and histological evaluations of radiotherapy for pineal tumors have appeared, the objective confirmation of its effectiveness during the course of irradiation has seldom been reported.

p RECOCIOUS puberty of intracranial origin has been the subject of exhaustive inquiry and numerous theories as to its causative mechanism have been advanced. The pineal region has been most frequently indicted in consideration of the production of this syndrome. Interest in this subject in the present instance was stimulated by a case of undoubted somatic and sexual precocity in which the lesion surgically exposed was an ectopic pineal tumor of the chiasmal region. The pertinent literature on ectopic pineal tumors and also that concerning precocity of intracranial origin has, therefore, been reviewed.

✓ Two cases of cavernous angiomas of the pineal region are presented. The possibility that a mass in the pineal region could be a cavernous angioma should be considered when deciding upon early surgery or a trial of radiotherapy.

✓ The authors present a new technique for surgery in the pineal region: a supracerebellar approach with the patient in the prone position. The surgeon sits on the left side of the patient, who lies prone with the head flexed and higher than the heart level (“Concorde position”). The main advantages of this arrangement over the sitting position include less fatigue on the part of the surgeon and decreased likelihood of air embolism. Fourteen patients have been operated on in this position. Pooling of blood in the operating field is rarely a problem.

✓ Endodermal sinus tumor (yolk sac carcinoma), a germinal neoplasm, is rarely primary in the cranial cavity. The authors add a third case with the tumor located in the anterior third ventricular (suprasellar) region to the literature. Seventeen previously reported intracranial cases, mostly in the pineal region, are briefly reviewed.

✓ The occurrence of pineal teratoma in two brothers is described, and the pathogenesis of this type of tumor is discussed. This is the first report of familial occurrence of pineal teratoma in two siblings.