Intracranial epidermoid tumor with changes in signal intensity on magnetic resonance imaging because of non-hemorrhagic pathology: case report

A 61-year-old woman presented an intracranial epidermoid tumor manifesting as dizziness and right facial hypesthesia. Magnetic resonance (MR) imaging revealed a well-defined lobulated mass in the right cerebellopontine angle as nearly isointense to the cerebrospinal fluid (CSF) on both T(1)- and T(2)-weighted images but inhomogeneously hyperintense on fluid-attenuated inversion recovery images. MR imaging performed 1 year later revealed that the tumor had significantly enlarged, and now appeared hyperintense to the CSF on T(1)- and T(2)-weighted images. The lesion was confirmed at surgery to be an epidermoid tumor filled with xanthochromic fluid. Histological examination found no evidence of hemorrhage in the resected tumor, so the changes in the MR imaging signal intensity were attributed to changes in the protein concentration of the intratumoral fluid, accumulation of debris, or some other non-hemorrhagic process.     

Combining steady-state constructive interference and diffusion-weighted magnetic resonance imaging in the surgical treatment of epidermoid tumors

We describe the usefulness of three-dimen-sional Fourier transformation-constructive interference in steady-state (CISS) imaging and diffusion-weighted imaging (DWI) in the pre- and postoperative magnetic resonance imaging evaluation of intracranial epidermoid tumors. Two surgically proven epidermoid tumors in the cerebellopontine (CP) angle were not identified in conventional T1- and T2-weighted images because of a signal intensity similar to that of cerebrospinal fluid (CSF). CISS images clearly demonstrated displacement of the cranial nerves and a shift caused by a lesion in the cistern, but the signal intensity of the tumor by CISS was not sufficiently different from that of CSF to demonstrate the tumor directly. Using DWI, the tumor in the cistern was shown clearly by its increased signal intensity. Together, CISS and DWI compensated for each other's disadvantages, and this combination was useful in guiding surgical treatment of epidermoid tumors in the CP cistern. Received: 8 October 1998 / Accepted: 15 December 1998     

Delayed postcontrast CT and MR imaging of chondroid chordoma--case report.

A rare case of intracranial primary chondroid chordoma is reported with special reference to neuroradiological findings. A precontrast computed tomographic (CT) scan revealed an isodense mass with multiple flecks in the right cerebellopontine region. A postcontrast CT scan showed slight ring enhancement. A delayed postcontrast CT scan demonstrated marked homogeneous enhancement extending from the middle cranial fossa to the cerebellopontine region on the right. Magnetic resonance (MR) imaging demonstrated a well-defined lesion as a high-intensity mass on T2-weighted image and a low-intensity mass on T1-weighted image. A MR image 5 minutes after gadolinium-diethylenetriaminepenta-acetic acid administration showed heterogeneous enhancement. A MR image 30 minutes after the contrast administration showed more marked, homogeneous enhancement. Such delayed postcontrast CT and MR imaging are useful in the differentiation of chondroid chordoma from classical chordoma.     

Acquired lumbar epidermoid cyst in an adult

A 61-year-old female complained of low back pain, and had been treated by spinal anesthetic injection more than 70 times over 14 years. Magnetic resonance (MR) imaging, performed at the age of 47 years, revealed no abnormal lesion. However, she developed irritable hypesthetic pain in the left leg at 61 years of age. MR imaging revealed a round mass appearing isointense on the T1-weighted and slightly hyperintense on the T2-weighted images. Laminectomy revealed an epidermoid cyst, which was removed. This case clearly demonstrates that adults can acquire epidermoid tumor which very probably has an iatrogenic origin. The incidence of epidermoid tumor is low, but we should be aware of the potential adverse complications such as formation of epidermoid tumors after lumbar puncture.     

Evaluation of MR imaging,digital subtraction cisternography,and CT cisternography in diagnosing CSF fistula

Summary Exact preoperative localization of the dural defect is an essential requirement for successful surgery of CSF fistula. Eighteen digital subtraction cisternography (DSC) results reported here were performed upon 16 patients with CSF rhinorrhea and 1 patient with CSF otorrhea. The exact site of the dural lesion could be proved in 9 out of 11 cases with active CSF leakage. In 4 cases the fistula was located in the cribriform plate, whereas it was found in the planum sphenoidale and the middle cranial fossa in 2 and 3 cases respectively. The frontal basal cisterns could not be filled sufficiently with the contrast agent due to haematoma and a prefixed chiasm accompanied by arachnoid adhesions in two cases. DSC performed during the non-drip period (3 cases) and in patients suspected to have a CSF rhinorrhea (3 cases) did not reveal the site of leakage.The investigation was followed by CT cisternography which allowed delineation of the lesion in the coronal view. In addition. MR with heavily T 2-weighted images (modification of the rapid acquisition with relaxation enhancement imaging) was performed upon 6 cases out of which the CSF fistula could be demarcated clearly in 4 patients, three with a traumatic CSF leakage and the other with an encephalomeningocele.Surgery performed successfully in 9 cases confirmed the predicted site of dural dehiscence.Being a dynamic investigation making the actual site of the CSF fistula visible, DSC is recommended in addition to CT cisternography which continues to be the most sensitive method for diagnosing dural and bony defects. It is suggested that heavily T 2-weighted MR images are useful in detecting the fistula in severe CSF rhinorrhea.Results presented as poster in part at the XIV Symposium Neuroradiologicum, London, June 1990.     

Extraaxial primitive neuroectodermal tumor mimicking a vestibular schwannoma: diagnostic and therapeutic difficulties. Report of two cases

Extraaxial cerebellopontine angle (CPA) medulloblastomas and other primitive neuroectodermal tumors (PNETs) are rare tumors. The authors report on two patients with PNETs who presented with progressive audiovestibular symptoms. In each case magnetic resonance (MR) imaging revealed an extraaxial lesion that filled the internal auditory meatus and exhibited the neuroimaging features of a vestibular schwannoma (VS). No high signal intensity was apparent in either the brainstem or adjacent cerebellum on T2-weighted MR images. Surgery with maximum resection (total in one case and subtotal in the other) was performed, followed by craniospinal radiotherapy. One year postoperatively, both patients were free from tumor. A CPA PNET mimicking a VS is a rare entity, the diagnosis of which is important because its treatment differs dramatically from that of VS, including prescribed surgery followed by conventional craniospinal radiotherapy.     

Posterior fossa epidermoid cysts presenting with unusual radiological appearances--two case reports

Intracranial epidermoid cysts generally appear as hypodense on computed tomography (CT), hypointense on T(1)-weighted magnetic resonance (MR) imaging, and hyperintense on diffusion-weighted MR imaging. We report two cases of posterior fossa epidermoid cysts with unusual radiological features. A 49-year-old male presented with facial dysesthesia and a 12-year-old male presented with diplopia and internuclear ophthalmoplegia. CT of both cases revealed hyperdense lesions. MR imaging showed the first case as hypointense in the posterior part and hyperintense in the anterior part of the tumor on diffusion-weighted imaging, and the second case as hyperintense on diffusion-weighted and T(1)-weighted MR imaging. Surgical exploration revealed that the tumors consisted of creamy materials, instead of the usual semi-solid or flaky texture in epidermoid cysts. Xanthochromic serous fluid was also contained in the superoposterior half of the cyst of the first case. These unusual contents of the cyst may be responsible for the unusual neuroimaging findings. Histological examination showed both cysts were lined with stratified squamous epithelium and contained keratinaceous materials. Therefore, epidermoid cysts can occasionally present with unusual radiological characteristics giving rise to a diagnostic pitfall.     

A case of primary meningeal melanocytoma of the left middle fossa

A 29-year-old woman presented with a primary meningeal melanocytoma of the left middle fossa manifesting as headache and nausea. Computed tomography (CT) with contrast medium demonstrated a clearly demarcated, homogeneously enhanced high density area surrounded by a cyst in the left temporal lobe. Magnetic resonance (MR) imaging showed the mass as a slightly high signal intensity area on the T1-weighted image and as a low signal intensity area on the T2-weighted image. Cerebral angiography revealed shift of the middle cerebral artery but no tumor stain. The solid part of the tumor had rapidly increased in size with reduction of the cyst 3 months later. Left frontotemporal craniotomy disclosed a clearly demarcated jet-black tumor attached to the dura. The black-colored lesion in the dura and the bone extended to the skull base, so malignant melanoma was a possibility. The solid part of the tumor was gross totally removed, and the dura and the skull bone were preserved. Histological examination of the tumor specimen revealed meningeal melanocytoma. Melanophages were present in the specimen of the black-colored lesion in the dura and the bone, but no neoplastic infiltration was present. The postoperative course was uneventful, and the patient's headache and nausea disappeared. CT and MR imaging taken 1 month later confirmed total removal of the tumor. No recurrence has been observed for 2.5 years after surgery. Preoperative differentiation of meningeal melanocytoma from malignant melanoma is difficult, but the primary goal of therapy is gross total resection of the solid part of the tumor irrespective of tumor type.     

The coexistence of basal epidermoid tumor and trigeminal neurinoma within the posterior fossa

Recently we encountered one case with basal epidermoid tumor originated in the cerebellopontine angle, associated with a trigeminal neurinoma of the Gasserian ganglion and trigeminal root within both middle and posterior fossa. We wish to present the case with an analytical review of the reported cases of multiple intracranial tumors. The patient was a 49-year-old man who noted the onset of left facial nerve palsy in March, 1974, which lasted for several years. In April 1976, he developed unsteadiness of gait which was not worsening. He noted left facial pain and paresthesias of tongue in October, 1981 and was pointed out as having left hearing disturbance by a physician. He was admitted to our hospital on December 11, 1981. Neurological examination showed hypalgesia and hypesthesia on his left face, left VII cranial nerve palsy and left-sided hearing loss. The IX and X cranial nerves were also involved with absent gag reflexes on the left side and swallowing difficulty. Tongue was deviated to the right on protrusion. He had mild ataxia of the left limbs, ataxic gait and horizontal gaze nystagmus to the right. He had neither café-au-lait spot nor subcutaneous tumor suggestive of von Recklinghausen's disease. CT scan revealed water density lesion in the prepontine and cerebellopontine cisterns which seemed to distort brainstem posteriorly. Metrizamide CT cisternography showed a large fungated mass filling the basal cistern. These findings strongly suggested the presence of an epidermoid tumor. A left suboccipital craniectomy was performed on May 13, 1982. A large pearly mass filling the basal cistern was removed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Olfactory neuroblastoma with intracranial extension. Report of two cases

Two cases of olfactory neuroblastoma with intracranial extension are described. The radiological features, including those of magnetic resonance (MR) imaging, are emphasized. On plain X-rays, the nasal cavity, ethmoid, sphenoid, and/or frontal sinuses were opacified. Erosion of the bony confines of the sinuses and orbit was seen in Case 1, but no bony destruction was observed in Case 2 despite intracranial tumor invasion via the seemingly intact cribriform plate. Angiography showed tumor staining in the ethmoid sinus, and in Case 1 tumor vessels were also found in the base of the frontal lobe. Computed tomography (CT) disclosed a large, soft, enhanced tissue mass occupying the nasal cavity and paranasal sinuses and extending into the anterior cranial fossa. In Case 1, MR images (0.5 Tesla) with a short spin echo sequence (repetition time [TR], 600 msec; echo time [TE], 26 msec) and a long spin echo sequence (TR, 2100; TE, 30, 60, 90) were obtained. T1-weighted images delineated the tumor accurately in relation to the normal architecture. T2-weighted images revealed widespread brain edema, with the tumor recognizable as a mass of low signal intensity within the high-intensity region of brain edema. The CT and MR imaging findings are by no means specific to olfactory neuroblastoma. However, both modalities, particularly MR imaging, are of special value in demonstrating the precise extent of the tumor in three dimensions.     

A case of cervical subpial lipoma

The authors report the rare case of a 48-year-old woman with a cervical subpial lipoma unassociated with spinal dysraphism. Her symptoms were progressive weakness and numbness in the four extremities and the neurological symptom of mild cervical myelopathy. Plain radiographs of the cervical spine showed diffuse widening of the spinal canal, which was occupied by a large low-density mass revealed by axial CT scan. MR imaging identified the mass as being dorsolateral to the cord in the intradural region. It was hyperintense on both T1- and T2-weighted images. Axial images with fat suppression sequence clearly showed dorsal nerve roots traveling through the lesions, but the interface between the spinal cord and lesion was not well demarcated. A cervical laminectomy between C3-6 revealed a yellowish subpial mass after the dura was opened. The mass was only partially resected and intraoperative SEP monitoring data remained normal including N20 latency. Histological examination found mature adipose tissue covered by thickened pia mater, which was compatible with a diagnosis of lipoma. After surgery, no complications occurred and the patient's myelopathy subsequently improved. Subpial spinal lipomas unassociated with dysraphism are uncommon and they are reported in only 1% of all spinal cord tumors. They are thought to arise from premature dysjunction of the cutaneous ectoderm during neural tube formation. Without any invasive procedure, MR imaging is indispensable to show their longitudinal dimension as well as their infiltrative extension into the spinal cord. The main purpose of surgery is to decompress the lipoma from the adjacent neural structures, because it is benign in nature and there is no cleavage plane identifiable between the lipoma and the spinal cord.     

Rapid spontaneous resolution of acute subdural hematoma occurs by redistribution--Two case reports

Coronal magnetic resonance imaging provided evidence of redistribution during the rapid spontaneous resolution of acute subdural hematoma (ASDH) in two patients. A 79-year-old female was transferred to our hospital after a traffic accident. Computed tomography (CT) on admission demonstrated an ASDH in the right frontal cerebral cortex. CT 12 hours after the accident revealed spontaneous resolution of the ASDH. Coronal magnetic resonance (MR) imaging 3 days after the accident clearly detected a very thin, sharply demarcated layer diffusely covering the cerebral convexity and the middle cranial fossa. A 41-year-old female fell and sustained head trauma with the loss of consciousness. CT on admission demonstrated an ASDH in the left frontal cerebral cortex. CT 12 hours after the accident revealed spontaneous resolution of the ASDH. Coronal MR imaging 3 days after the insult clearly demonstrated the redistribution and dispersal of the hematoma. Although CT showed the disappearance of the hematoma, MR imaging demonstrated redistribution rather than disappearance of the blood in both cases. These cases indicate that spontaneous resolution of ASDH occurs by redistribution and dispersal of the hematoma.     

Pertreatment radiation induced oedema causing acute hydrocephalus after radiosurgery for multiple cerebellar metastases

Summary ¶Background. Most complications of radiosurgery occur after 6–12 months and some long term complications up to after 5–10 years. Although severe, immediate side effects are rare, we report a patient who shows that this possibility should be taken into account when large volumes are treated especially in the posterior fossa. Case report. A patient was treated with radiosurgery for multiple brain metastases, of which 5 were located in the posterior fossa. Deterioration occurred, radiosurgery was halted abortion and CT showed acute hydrocephalus caused by a significant edema in the posterior fossa, not present in an MR examination performed some 6 hours earlier. After intubation and external ventricular CSF drainage, a permanent shunt was inserted, the edema resolved, and the patient recovered to her pretreatment condition within 10 days. The remaining metastases were treated during the first session and MR images showed the hydrocephalus resolved when all the radiated tumors had significantly decreased in size. Interpretation. Care should be taken when treating with radiosurgery patients posterior fossa metastases and signs of compressed CSF pathways. Exceptionally, an acute radiation induced edema could result in a block of the CSF pathways, necessitating a surgical intervention. Prophylactic shunt insertion or hospitalization the night following the treatment should be considered.Published online July 23, 2003     

Medulloblastoma of the cerebellopontine angle--case report

A 21-year-old male patient presented with a rare cerebellopontine angle medulloblastoma manifesting as cerebellar and long tract involvement signs and symptoms. The clinical and radiological characteristics of the lesion were similar to extraaxial lesions of cerebellopontine angle. The histological diagnosis of the lesion was medulloblastoma. Surgery achieved partial removal and was followed by radiotherapy and chemotherapy. The patient remained well after 18 months. Medulloblastoma of the cerebellopontine angle is a relatively rare clinical entity and may occur as a dural-based extraaxial mass.     

Regression of Symptomatic Syringomyelia after Resection of Posterior Fossa Tumour

Summary.  Syringomyelia associated with posterior fossa tumours is a very infrequent combination of pathological entities. The few cases which have been reported generally were asymptomatic in respect of the spinal cavitations. The authors report on a 36-year-old woman with a large extradural posterior fossa epidermoid tumour with a concomitant holocord symptomatic syringomyelia. Some of her symptoms were clearly attributed to the intraspinal cavitation. The lesions were both diagnosed by magnetic resonance imaging (MR). The patient did well after surgery of the brain lesion, with an objective improvement in her neurological status and a complete resolution of the syrinx documented by the MR 7 months after tumour removal.  Syringomyelia in this case could be explained by blockage of the cerebrospinal fluid (CSF) circulation at the foramen magnum which in turn resulted in cranio-spinal pressure dissociation. This led to an accumulation of extracellular fluid (ECF) in the central canal, starting cavitation. Consequently, the syrinx was slowly expanded by the long-standing “slosh” effect of the systolic pressure waves. However, also via a distortion mechanism within the posterior fossa a pathologically plugged obex could have contributed to syrinx formation by means of preventing drainage of fluid from the ventricular CSF system.     

Two cases of the epidermoid on the petrous bone

Epidermoids known as cholesteatomas, are congenital benign tumors and originate in the embryonic ectoderm. They account for 1.3% of all intracranial tumors. They are often found in the cerebellopontine angle and the paraseller region, but rarely in the petrous portion of the temporal bone. Epidermoids of the petrous bone tend to slowly present progressive facial palsy and hearing disturbance. In this article, two cases of epidermoids involving the petrous bone are reported. A 55-year-old male presented left facial palsy, left hearing disturbance and decreased gustation in the left side of the tongue. MRI revealed a non-enhanced mass on the petrous portion of the left temporal bone, and bone-window CT showed bone destruction in the same region (Case 1). A 71-year-old female was aware of left facial palsy and left hearing loss for 15 years. MRI showed a non-enhanced mass on the petrous bone, and bone-window CT demonstrated extensive bone erosion of the petrous bone and the middle cranial fossa (Case 2). In both cases, total removal was performed via the middle cranial fossa approach. Both tumors existed extradurally and had pressed against the genicurate ganglion of the facial nerve. The facial palsy of the former case recovered 12 months after surgery. We discuss the problems of diagnosis and treatment of epidermoids of the petrous bone.     

Choroid plexus metastasis of lung carcinoma--case report.

Metastatic tumors in the choroid plexus are generally considered to be very rare. The authors present a case of lung large cell carcinoma with a single metastatic tumor in the choroid plexus of the lateral ventricle trigone. Precontrast computed tomographic (CT) scans showed an isodensity mass with extensive peritumoral edema, which was considerably enhanced on the postcontrast CT scans. Magnetic resonance (MR) images demonstrated the mass as a low-intensity area on the T1-weighted image and an iso-intensity area on the T2-weighted image. The tumor was clearly differentiated from the peritumoral edema by both CT and MR imaging. The diagnosis was confirmed by surgery.     

Epidermoid tumor with unusual CT and MR findings--case report.

The authors report a case of epidermoid tumor attached to the dura of the frontal convexity and extending into the cerebral parenchyma, with unusual computed tomographic (CT) and magnetic resonance (MR) findings. The tumor appeared as a mixed density intracerebral mass containing dense calcifications on the precontrast CT scan, and the capsule was intensely enhanced on the postcontrast scan. It appeared as a mixed intensity lesion on both the T1- and T2-weighted MR images.     

Malignant squamous degeneration of a cerebellopontine angle epidermoid tumor. Case report

The authors present the case of a woman with a cerebellopontine angle (CPA) epidermoid cyst that degenerated into a squamous cell carcinoma. Malignant degeneration of an epidermoid cyst is an extremely rare occurrence. Malignant transformation must be considered in the differential diagnosis when new contrast enhancement on imaging studies and progressive neurological deficit are seen in a patient harboring an epidermoid cyst. The patient initially presented with a 10-year history of left trigeminal neuralgia, subacute left-sided hearing loss, and with facial weakness of 3 weeks' duration. Initial magnetic resonance (MR) imaging revealed a left CPA mass, consistent with an epidermoid. There was faint contrast enhancement where the tumor was in contact with the lateral brainstem. A subtotal resection was performed. Histopathological findings were consistent with an epidermoid tumor. One year after initial presentation, the patient's neurological deficit had increased, and follow-up MR imaging demonstrated a large contrast-enhancing tumor filling the left CPA and compressing the brainstem. At repeated surgery a squamous cell carcinoma arising from the previous epidermoid was found. The patient was subsequently treated with external-beam radiotherapy and stereotactic radiosurgery. Her tumor stabilized. Three years and 8 months after the patient's initial presentation, a new area of tumor developed at the torcular Herophili. The patient died shortly thereafter. Malignant squamous degeneration is a rare cause of enhancement on MR images, as is progressive neurological deficit in a patient with an epidermoid. The combination of subtotal resection, external-beam radiotherapy, and stereotactic radiosurgery may be useful for local tumor control but the long-term prognosis is guarded.