Unusual presentations of cerebral solitary fibrous tumors: report of four cases

OBJECTIVE AND IMPORTANCE: Four rare cases of central nervous system solitary fibrous tumors (C-SoFTs) are described. This tumor has not previously been reported in children or in deep cortical structures. Three of these tumors occurred in the posterior fossa. Only four cases in the posterior fossa have been described previously. Nine years after its debulking from the posterior fossa, one tumor disseminated to the spine, lung, and liver. Only one such aggressive C-SoFT has been described previously. CLINICAL PRESENTATION: A 7-year-old child had had 1 year of right-sided weakness at presentation. Magnetic resonance imaging scans revealed a left basal ganglia lesion. A 49-year-old woman and a 30-year-old man presented after experiencing headaches for months. Magnetic resonance imaging scans in these patients revealed a tumor in the fourth ventricle and right jugular foramen, respectively. A 55-year-old man had spinal, liver, and lung dissemination of a previous posterior fossa tumor at presentation. INTERVENTION AND TECHNIQUE: All four patients underwent craniotomy for resection or subtotal removal of the tumor. Intraoperative observations noted solid well-encapsulated tumors. Immunohistochemistry confirmed C-SoFTs in all four cases. CONCLUSION: C-SoFTs are rare central nervous system, typically dural-based, tumors. They frequently are overlooked in the differential diagnosis of solid central nervous system tumors. Our findings suggest that these tumors can occur at any age and in most locations, regardless of proximity to the meninges (basal ganglia and ventricle), suggesting that the cells of origin are not meningothelial, but rather the mesenchyme of the cerebral vasculature. T1- and T2-weighted magnetic resonance imaging was notable for areas of hypointensity and of hyperintensity best described as patchy or a ying-yang appearance in all cases. Delayed extracranial metastasis may be noted.     

Tumors originating in the ischioanal fossae: Report of cases

Tumors originating in the ischioanal fossa are rare. Such tumors present problems interesting in differential diagnosis and treatment.The subjective symptoms caused by tumors of the ischioanal fossa, as shown by these cases, are not definitely peculiar to the lesion but in general include painless, progressive swelling which causes difficulty on sitting or defecation. The findings of asymmetry in the ischioanal region, overlying normal skin, and circumscribed movable tumor mass that is not tender are of value in differential diagnosis.These tumors should always be excised and the tissue examined microscopically for the correct diagnosis.     

Medulloblastoma presenting with tentorial "dural-tail" sign: is the "dural-tail" sign specific for meningioma?

To the best of our knowledge, the association of a medulloblastoma with a "dural-tail" sign has not been previously reported. A 24-year-old male developed severe headaches and right-sided dysmetria that worsened over 1 month. Magnetic resonance (MR) imaging of the brain demonstrated a heterogeneously enhancing lesion in the posterior fossa. The lesion appeared to be tentortally-based and exhibited a characteristic "dural-tail" sign, which is considered pathognothonic for meningioma. Cerebellar tonsil ectopia and hydrocephalus were also present. The presumptive diagnosis of tentorial meningioma was made. The lesion was resected by a posterior fossa approach. At surgery, the appearance of the tumor was inconsistent with the diagnosis of meningioma, and histopathologic evaluation yielded the diagnosis of medulloblastonia. This case and the literature demonstrate that malignant tumors can present with the characteristic MR imaging appearance of a meningioma. This possibility must be considered when treatment is planned, especially if a nonoperative course is favored.     

Medulloblastoma Presenting with Tentorial “Dural-Tail” Sign: Is the “Dural-Tail” Sign Specific for Meningioma?

To the best of our knowledge, the association of a medulloblastoma with a “dural-tail” sign has not been previously reported. A 24-year-old male developed severe headaches and right-sided dysmetria that worsened over 1 month. Magnetic resonance (MR) imaging of the brain demonstrated a heterogeneously enhancing lesion in the posterior fossa. The lesion appeared to be tentortally-based and exhibited a characteristic “dural-tail” sign, which is considered pathognothonic for meningioma. Cerebellar tonsil ectopia and hydrocephalus were also present. The presumptive diagnosis of tentorial meningioma was made. The lesion was resected by a posterior fossa approach. At surgery, the appearance of the tumor was inconsistent with the diagnosis of meningioma, and histopathologic evaluation yielded the diagnosis of medulloblastonia. This case and the literature demonstrate that malignant tumors can present with the characteristic MR imaging appearance of a meningioma. This possibility must be considered when treatment is planned, especially if a nonoperative course is favored.     

Supratentorial meningeal melanocytoma mimicking a convexity meningioma

Summary Objective and importance. Meningeal melanocytomas are rare benign neuro-ectodermal tumors arising from melanocytic cells in the leptomeninges. These leptomeningeal melanocytes are found at highest density underneath the brain stem and along the upper cervical spinal cord. Thus, most reported cases of meningeal melanocytomas are located in the posterior fossa and the spinal cord, respectively. Clinical presentation. We report on the rare case of a 55-year-old male patient with a large supratentorial meningeal melanocytoma mimicking a convexity meningioma and a smaller, similarly dura based lesion in the posterior fossa. Intervention. Tumor control to date was achieved by surgery of the large lesion and radiosurgery of the small lesion. Conclusion. Complete tumor resection may be advantageous and second or recurrent lesions may be managed by repeat surgery or stereotactic radiosurgery.     

Adjacent epidermoid cyst and primary central nervous system lymphoma: case report

BACKGROUND: Except for cases with radiotherapy or phacomatosis, multiple primary brain tumors of different histologic types are rare. The authors report the association of an epidermoid cyst and a primary CNS lymphoma. CASE DESCRIPTION: A 66-year-old man with a 20-year history of gait disturbance was admitted because of recently worsening symptoms. Magnetic resonance imaging showed an abnormal mass in the posterior fossa. The mass lesion had the appearance of a cystic tumor with a large mural nodule. Gross total removal of the tumor was performed. Histologic examination disclosed the cystic portion to be an epidermoid, whereas the nodular portion exhibited the histologic and immunohistochemical features of a malignant lymphoma. The lymphoma cells were shown to harbor EBV by in situ hybridization. CONCLUSIONS: To our knowledge, this is the first report of the coexistence of an epidermoid cyst and primary CNS lymphoma. When the lesions are adjacent, a definite preoperative diagnosis can be difficult. Epstein-Barr virus-associated CNS lymphoma is rare among the immunologically normal population. The possible pathogenesis for the coexistence of these 2 tumors is discussed.     

Coexistence of intracranial meningioma and primary malignant lymphoma--case report.

The authors present a case of multiple primary intracranial tumors of different cell types. A 62-year-old female presented with symptoms suggestive of an intracranial mass lesion. Computer tomographic scans revealed two lesions, one in the right temporal lobe and one in the posterior fossa. Both tumors were approached in one operation. The right temporal tumor was diagnosed as primary malignant lymphoma, and the right posterior fossa tumor as meningioma. Phacomatosis was ruled out as a possible etiology. Multiple primary intracranial tumors of different cell types are rare, and this is the first report of coexistent intracranial meningioma and malignant lymphoma.     

Holoprosencephaly accompanied with dysgenesis of the cerebellum]

We have encountered 9 cases of holoprosencephaly, four of them with abnormalities of the posterior fossa. Three cases of semilobar type had severe cerebellar hypoplasia and a large cyst continuing to the fourth ventricle. They were diagnosed as Dandy-Walker syndrome. A case of lobar type had a relatively mild form of cerebellar hypoplasia and it was thought to be a Dandy-Walker variant. MRI was able to clarify the anatomical relationship of the intracranial construction, for example monoventricle, dorsal sac or large cyst in the posterior fossa, and it was very useful for the diagnosis of these congenital anomalies. All of them showed hydrocephalus and required treatment with ventriculoperitoneal or cyst-peritoneal shunt. With the availability of MRI, easy diagnosis of the mild forms of holoprosencephaly has been facilitated, and accompanying anomalies are also able to be diagnosed. Up to now, the structure of the posterior fossa in holoprosencephaly was thought to be normal. However, several cases of holoprosencephaly accompanied with cerebellar hypoplasia and cystic lesion of the posterior fossa, revealed by MRI or autopsy, have been reported. It was suggested that holoprosencephaly with anomalies of the posterior fossa may be less rare than has been thought, so far.     

Posterior fossa hemorrhage caused by dural arteriovenous fistula: case reports

BACKGROUND: Relatively few reports are available on dural arteriovenous fistulas (AVFs) accompanied by posterior fossa hemorrhage. We now report upon two such cases and discuss the differential diagnosis and imaging findings. CASE DESCRIPTION: A 36-year-old man was admitted after experiencing sudden headache. Computerized tomography (CT) showed vermian and fourth ventricular hematoma, and magnetic resonance imaging (MRI) revealed an abnormal signal void. Angiography demonstrated a dural AVF in the region of foramen magnum. The second case, a 57-year-old man, was also admitted for the evaluation of headache. CT scan revealed tentorial subdural, subarachnoid and vermian hemorrhage. MRI showed vermian hematoma and an abnormal signal void below the tentorium. Angiography demonstrated a dural AVF in the tentorium.The first case underwent transarterial embolization, after which the dural AVF disappeared completely. The second case underwent craniotomy immediately after failure of endovascular therapy. Postoperative angiography demonstrated no remaining dural AVF. CONCLUSIONS: Dural AVF should be considered as a causative lesion in cases with posterior fossa hemorrhage with no other definitive cause.     

A case report of sphenoidal encephalocele presenting with cerebral spinal fluid rhinorrhea

Sphenoidal encephalocele is a rare congenital anomaly. We report a case of sphenoidal encephalocele presenting with cerebral spinal fluid rhinorrhea. A 53-years-old man suffered recurrent fever and rhinorrhea. Computed tomography demonstrated a low density area extending from the left middle cranial fossa into the left sphenoidal sinus. Bone defect was identified in the medial surface of the left middle cranial fossa. Magnetic resonance imaging with contrast medium demonstrated peripheral enhancement of the lesion. We diagnosed the lesion as sphenoidal encephalocele. Surgical repair and amputation of the encaphalocele was performed. Sphenoidal encaphalocele should be considered as a possible diagnosis for recurrent fever and rhinorrhea.     

Reverse brain herniation during posterior fossa surgery

Posterior fossa tumors are commonly associated with obstructive hydrocephalus. Relieving the raised intracranial pressure by draining the cerebrospinal fluid presents the possibility of reverse herniation of the brain. A 5-year-old male child with a diagnosis of posterior fossa space-occupying lesion and hydrocephalus was scheduled for craniectomy in the prone position. After craniectomy, the surgeons placed an intraventricular shunt catheter to drain out cerebrospinal fluid in an attempt to reduce the tense brain so as to facilitate easy dissection of the tumor. The patient had sudden and severe bradycardia followed by asystole. A diagnosis of reverse coning was made. Immediately, the surgeon injected 10-15 mL normal saline into the ventricles. There was a spontaneous return of the sinus rhythm and the rest of the course of surgery was uneventful. We present this case showing a rare phenomenon and its successful management.     

Neurenteric cyst of the posterior fossa. Case report and review of the literature

Intracranial neurenteric cysts are rare entities. The term is currently used to describe epithelial cysts that are lined with a presumed endodermal-derived epithelium and are mostly located in the posterior fossa.Preoperative diagnosis is often difficult because of their clinical presentation, which may resemble a subarachnoid hemorrhage, and the radiological aspect, which can mimic vascular pathologies.We describe a posterior fossa neurenteric cyst in a 27-year-old woman, who presented with sudden headache as the only symptom and who was addressed to our hospital for subarachnoid hemorrhage. Diagnostic angiography was negative and MRI revealed a prepontine cystic lesion. The patient underwent a posterolateral approach on the right side, with subtotal resection of the lesion.We discuss the embryologic, diagnostic and therapeutic aspects of these cysts and review the literature.     

Pathogenesis and diagnostic pitfalls of ventricular diverticula: case report and review of the literature

OBJECTIVE AND IMPORTANCE: Ventricular diverticula are local herniations of the ventricular system occurring in association with severe, long-standing hydrocephalus. Variability in the extent and location of these ventricular pouches may produce misleading radiological conformations and raise diagnostic challenges. In this report, we discuss the pathogenesis and differential diagnosis of ventricular diverticula on the basis of a case illustration. CLINICAL PRESENTATION: We report the case of a 38-year-old woman presenting with hydrocephalus secondary to an obstructive lesion of the third ventricle. A large, dilated structure compressing the brainstem was present in the posterior fossa. INTERVENTION: The posterior fossa lesion was identified as an atrial diverticulum by injection of contrast medium into the right lateral ventricle, which led to immediate enhancement of the infratentorial cavity. Ventricular drainage and removal of the third ventricular lesion, a colloid cyst, allowed progressive collapse of the diverticulum and symptom resolution. CONCLUSION: This report discusses the pathogenesis of ventricular diverticula and demonstrates that ventriculography can be used to differentiate atrial diverticula from other posterior fossa lesions when time-consuming multiplanar magnetic resonance imaging cannot be afforded on an emergency basis.     

Pseudoaneurysma an der kindlichen Arteria poplitea nach arthroskopischer Meniscusresektion

Arterial injuries following arthroscopic procedures are extremely rare, but may have dramatic consequences without early diagnosis and appropriate treatment. We report a case of popliteal artery pseudo-aneurysm a following arthroscopic meniscectomy in a child. Non-invasive diagnostic workup included Doppler flow color imaging and computed tomography with contrast and 3D workup. The arterial lesion was repaired surgically by an posterior approach using a vein patch plasty. The popliteal artery is in close relationship to the posterior capsule of the knee joint. During knee flexion the vessel is positioned forward and placed even closer to the horn of the lateral meniscus. For this reason arthroscopic surgical manipulation in the posterior aspects of the knee joint must be performed under direct visualization. Indistinct swelling in the popliteal fossa and calf following arthroscopic surgery should arouse suspicion of an arterial injury.     

Neoplasm of Endolymphatic sac Origin: Clinical, Radiological and Pathological Features

Summary  This paper reports on a 55-year-old female who had undergone middle ear surgery 12 years previously and was admitted with a 6-months history of unilateral hearing loss and facial weakness. MRI and CT demonstrated a space-occupying lesion arising from the temporal bone and extending into the posterior fossa. Treatment consisted in complete tumour removal. Temporal and mastoid bone destruction associated with typical histological features led to the diagnosis of neoplasm of endolymphatic sac origin. Clinical, histological, radiological and intra-operative features of these rare tumours are described and discussed. The pertinent literature is reviewed.     

Contralateral trigeminal nerve dysfunction as a false localizing sign in acoustic neuroma: a clinical and electrophysiological study

A 49-year-old woman presented with right facial sensory impairment due to trigeminal nerve dysfunction caused by a contralateral acoustic neuroma. The mechanism of the falsely localizing trigeminal involvement is probably displacement and distortion of the brain stem by the large mass lesion and not increased intracranial pressure. A preoperative orbicularis oculi reflex study was abnormal and indicative of right trigeminal nerve dysfunction; after surgical removal of the tumor, the orbicularis oculi reflex study was normal. We conclude that a false localizing sign of trigeminal nerve dysfunction can occur rarely on the contralateral side in patients with large posterior fossa tumors, especially tumors arising from the cerebellopontine angle, and should be considered in the differential diagnosis of hemifacial sensory disturbance.     

Dysplastic gangliocytoma of the cerebellum: Rare differential diagnosis in space occupying lesions of the posterior fossa

Dysplastic gangliocytoma of the cerebellum (Lhermitte-Duclos) is a rare space occupying lesion of the posterior fossa with some typical neuroradiological features which can be better diagnosed in the MRI era. This is the major CNS manifestation of Cowden disease. In recent years more publications underlined the association of these hamartomatous lesions. We add another patient with a dysplastic gangliocytoma of the cerebellum who also had a thyroid adenoma and fulfilled the criteria of having Cowden disease.A problem of surgical removal of these tumors is missing the borderline between tumor and healthy cerebellum tissue so that incomplete removal of the tumor is not rare. Surgical removal of these tumors in an open MRI unit would be a good indication.     

Glioblastoma of the cerebellum. A report of 3 cases

Glioblastoma (GBM) is one of the commonest intra cranial tumors. Infratentorial GBM is, however, a rare entity. We report 3 cases of histologically proven posterior fossa GBM. The clinical presentation was of a rapidly growing posterior fossa mass. The diagnosis was made only on histological examination. The radiological features are non-specific and the clinical course same as GBM elsewhere. We describe their clinical presentation, radiological and pathological features and a review of describe the literature.     

Arachnoid cysts of the posterior fossa

A series of 6 patients with arachnoid cysts of the posterior fossa who were treated surgically is presented. The diagnosis of the nature of the lesion and of the exact location within the posterior fossa could not be established on a clinical basis. CT scanning is the best method for diagnosing the lesion and for observing the postoperative evolution. Treatment consisted of removing the cyst walls, shunting the cyst to the peritoneum, or both. The differential diagnosis of arachnoid cysts of the posterior fossa from other cerebrospinal fluid collections, such as the megacisterna magna or the Dandy-Walker malformation, are discussed.