Intradiploic arachnoid cyst identified by diffusion-weighted magnetic resonance imaging--case report

A 72-year-old woman presented with an intradiploic arachnoid cyst in the occipital intradiploic space which was found incidentally by magnetic resonance (MR) imaging. Computed tomography revealed a widened diploic space and thinning of the inner and outer tables of the occipital bone. The cyst appeared as isointense to the cerebrospinal fluid on both T1- and T2-weighted images. The differential diagnosis of intradiploic epidermoid cyst could be excluded because the lesion was low intensity on diffusion-weighted MR images. Arachnoid cyst is a benign lesion, so exploratory surgery should be avoided unless the cyst is symptomatic. Diffusion-weighted MR imaging is an effective modality to distinguish diploic epidermoid cysts from arachnoid cysts.     

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.     

Multiple epidermoid cysts located in the pineal and extracranial regions treated by neuroendoscopy

A 22-year-old woman presented with a rare case of multiple epidermoid cysts located in the pineal and extracranial regions. Magnetic resonance (MR) imaging showed a lesion in the pineal region as hypointense on the T(1)-weighted image and hyperintense on the T(2)-weighted image, without enhancement. Neuroendoscopic treatment was performed under a diagnosis of pineal cyst. However, the cyst wall was too thick to perforate, although third ventriculostomy was performed. Diffusion-weighted MR imaging demonstrated the lesions in the pineal and extracranial regions as marked hyperintensity. The diagnosis was epidermoid cyst. Subsequently, neuroendoscopic treatment of the pineal epidermoid cyst was performed. Careful preoperative diagnosis of epidermoid cysts based on diffusion-weighted MR imaging is required.     

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.     

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.     

Rathke cleft cyst intracystic nodule: a characteristic magnetic resonance imaging finding

OBJECT: The fluid content of Rathke cleft cysts (RCCs) displays variable appearances on magnetic resonance (MR) images and can appear indistinguishable from other intrasellar or suprasellar cystic lesions. Intracystic nodules associated with individual RCCs have been noted, but to date their significance has not been fully explored. METHODS: The authors retrospectively reviewed MR imaging studies obtained in patients harboring intrasellar or suprasellar lesions that were consistent with RCCs to identify the presence and imaging characteristics of intracystic nodules. An intracystic nodule was present in nine (45%) of 20 patients with an RCC. All intracystic nodules were clearly visible and displayed a characteristic low signal intensity on T2-weighted MR images. The nodule was only visualized on T1-weighted images in four cases, in which it exhibited a consistent high signal intensity similar to that of the cyst fluid. The nodules did not enhance following the intravenous administration of a contrast agent. CONCLUSIONS: Although it is difficult to differentiate RCCs from other sellar cystic lesions because of the variable signal intensities displayed on MR images, the intensity of the intracystic nodule seems consistent on T1- and T2-weighted images, and the nodule is always clearly visible on T2-weighted images. With a nonenhancing cystic lesion that does not cause significant symptoms in the patient, the identification of an intracystic nodule with a characteristic signal intensity will aid in the diagnosis of RCC and the selection of conservative management.     

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     

Epidermoid cysts of the brain stem. Report of three cases

The authors report the cases of three patients with epidermoid cysts which insinuated themselves into the brain stem. In all three patients, the tumor occupied the pons, although in one it was predominantly located in the medulla. The cyst contents and nonadherent tumor capsule were removed in all three patients, but no attempt was made to remove tumor densely adherent to the brain stem. One patient's cyst was removed in one operation, but maximal resection in the other two required two operations. After surgery, sixth nerve function completely returned in one patient; another patient had a stable pontine gaze palsy but developed new facial weakness; and the third patient had stable cranial nerve deficits with a diminished hemiparesis. The last patient developed a pseudomeningocele and communicating hydrocephalus, and required a lumboperitoneal shunt. In all three patients, computerized tomography scans demonstrated hypodense tumors not enhanced by contrast material. Magnetic resonance imaging was performed on two patients; in both, the tumors showed increased signal intensity relative to brain on T1-weighted images and decreased signal intensity relative to brain on T2-weighted studies. Magnetic resonance imaging, the most accurate modality for localizing these lesions and determining their extent, was also invaluable for postoperative monitoring and follow-up evaluation. Safe and adequate resection includes decompression of cyst contents and removal of nonadherent portions of the cyst capsule. Cyst wall adherent to the brain stem, however, should not be removed.     

Retrodental synovial cyst which disappeared after posterior C1-C2 fusion: A case report

Synovial cysts of the cervical spine are extremely rare. We describe an 8-year-old boy with atlantoaxial subluxation and hypoplasia of the dens. Magnetic resonance imaging showed a round lesion, posterior to the odontoid process. This mass was characterized by a low signal intensity on T1-weighted images, and high signal intensity on T2-weighted images. The retrodental synovial cyst disappeared after posterior atlantoaxial arthrodesis.     

Involuted intraosseous lipoma of the sacrum showing high signal intensity on T1-weighted magnetic resonance imaging (MRI)

Involuted intraosseous lipoma with extensive fat necrosis resulting in cyst formation (Milgram stage III) is distinguishable from lesions without necrosis (stage I) or lesions with focal fat necrosis (stage II), based on differences in signal intensity on magnetic resonance imaging (MRI). Fat tissue has a high signal intensity on both T1- and T2-weighted MR images, whereas the extensive fat necrosis that results in cyst formation shows high signal intensity on T2-weighted images and low intensity on T1-weighted images. We report a patient in whom an intraosseous lipoma with high signal intensity on both T1- and T2-weighted MRI was found to be extensively involuted on histopathologic examination. Intraosseous lipoma appears to undergo spontaneous involution. In some patients, therefore, surgical excision may not be necessary. A correct preoperative diagnosis should reduce the necessity for a biopsy or surgery. Although lesions classified as stage I or II are easily identified by MRI, those of stage III are difficult to diagnose preoperatively by this method. Received: May 12, 1998 / Accepted: November 7, 2000     

Diagnosis and surgical treatment of spinal hemangioblastoma

Spinal hemangioblastoma is a rare tumor. Its incidence varies from 1.6 to 2.1% of primary spinal cord tumors. In this report, the authors described MRI (magnetic resonance imaging) of spinal hemangioblastoma and its surgical results. [MATERIALS AND METHODS] This series included 10 spinal hemangioblastomas studied with CT or MRI. There were 8 men and 2 women. The age ranged from 21 to 68 years, with a mean age of 45 years. 6 patients were preoperatively and postoperatively studied with a resistive 0.15 T system (Toshiba MRT 15A) or a superconductive 1.5 T system (GE Signa or Siemens Magnetom). The lesions were single in 8 out of 10 patients and multiple in 2. 10 spinal hemangioblastomas were located in intramedullary space and 2 in both intramedullary and extramedullary space. 8 out of 10 patients (80%) were associated with cyst. [RESULTS] (1) MRI In T1-weighted MR images after administration of Gd-DTPA, the solid component of the tumor enhanced brilliantly. The enhanced lesions contained serpiginous areas of signal void, reflecting vascular structures in 5 out of 6 cases. The intrinsic spinal cord signal was heterogenous with low intensity areas representing the associated cyst. The cyst appeared either isointensive to cerebrospinal fluid (CSF) or hyperintense relative to CSF and slightly hypointense relative to the spinal cord. The precise delineation of the tumor was impossible without enhancement. Noncontrast T1-weighted MR images displayed diffuse widening of the spinal cord. On T2-weighted MR images, all regions of the spinal cord enlargement increased in signal. (2) Postoperative results All 10 cases of spinal hemangioblastomas were totally removed with good postoperative results and the associated cysts were drained. The postoperative MRI showed the disappearance of the tumor and significant reduction in the size of the cyst. [CONCLUSION] (1) Gd-DTPA enhanced MRI was useful in defining and outlining the solid component of spinal hemangioblastoma. (2) The complete removal of the tumor with only drainage of the cyst was possible with good postoperative results.     

脊髓内胆脂瘤的诊断和手术治疗

目的提高脊髓内胆脂瘤的诊断水平及选择治疗方法。方法总结１９７８～１９９５年收治的经手术和病理证实的１０例脊髓内胆脂瘤的经验。结果患者临床表现无特异性。本组ＣＴ检查８例，显示肿瘤呈现均匀低密度影像，边界清楚，强化扫描多无增强。ＭＲ检查４例，肿瘤呈现信号强度变化不定的特点，边界清楚。１０例患者均行手术治疗，肿瘤全切除１例，次全切除９例。８例术后得以随访，无复发。结论肿瘤全切是治疗本病的最好选择。     

膝关节髌下脂肪垫区肿瘤的MRI诊断

目的:研究发生于膝关节髌下脂肪垫区肿瘤或肿瘤样病变及其MRI表现。方法:回顾性研究14例经手术病理证实的膝关节髌下脂肪垫区的肿瘤或肿瘤样病变的MRI表现。分析病变的MRI形态、平扫与增强的信号特点。结果:14例15个病灶,滑膜腱鞘巨细胞瘤7例,肿块T1WI呈等信号或稍高信号,T2WI呈等信号5例,高信号肿块内有含铁血黄素低信号灶2例,轻度或不强化。髌下脂肪垫内海绵状血管瘤2例,T1WI呈等信号,T2WI呈显著高信号,明显强化。囊肿4例,T1WI低信号,T2WI呈高信号,无强化。滑膜纤维脂肪瘤2例,T1WI呈等或高信号,T2WI呈高信号。结论:膝关节髌下脂肪垫区可发生多种肿瘤或肿瘤样病变,以滑膜腱鞘巨细胞瘤、海绵状血管瘤及滑膜囊肿多见。MRI表现具有一定的特征性,不失为术前定性诊断的有效方法。     

A case of pineal epidermoid cyst showing an interesting magnetic resonance imaging

A case of pineal epidermoid cyst with interesting findings of magnetic resonance imaging (MRI) is reported referring to the literature. In our case, homogeneous high density area is seen on CT and high signal intensity is recognized on T1-weighted MRI and low signal intensity on T2-weighted MRI.     

Intratumoral hemorrhage of cholesterol granuloma in the frontal bone showing rapid progressive symptoms: a case report

A 30-year-old man developed an exopthalmus in his right eye and diplopia at upward gaze those were progressive in two days. On admission, his upper eye lid in the right eye swelled and upward gaze was limited in the right eye. CT scan showed an osteolytic lesion in the right frontorbital bone. MR imaging showed a high signal tumor in both T1- and T2-weighted imaging with sharp margin and no enhancement. Right frontal craniotomy was performed and the cystic tumor consisting of old hematoma, and soft tissue surrounding the cyst was totally removed. The orbital roof had a large defect and tumor compressed periorbita. Neither communication with the frontal sinus nor mucosa with inflammation were seen. The postoperative course was uneventfull and pathological diagnosis was cholesterol granuloma with hematoma. Orbitofrontal bone is a rare site to have cholesterol granuloma. Most of them are asymptomatic. In our case, intratumoral hemorrhage caused compression on the perioribital, leading to a progressive mass sign. Preoperative differential diagnosis from other orbital tumors, such as epidermoid and lipoma was difficult.     

Adrenal cyst: A review of the Japanese literature and report of a case

Adrenal cysts are a rare condition and are usually non-functioning and asymptomatic. A 44-year-old man was referred from another hospital because a left retroperitoneal tumor was incidentally found by abdominal echography. Laboratory findings including adrenal hormonal study were within the normal range. It showed homogeneously low intensity on T1-weighted images and high intensity on T2-weighted images on magnetic resonance imaging (MRI). Angiography demonstrated that the tumor was avascular and of left adrenal origin. The patient was diagnosed with left adrenal cyst and was intensively followed up with plans for examination with diagnostic imaging.     

Neuroendoscopic approach to tectal tumors: a consecutive series

OBJECT: The authors report a consecutive series of 10 patients who presented with signs and symptoms caused by tectal tumors. Clinical findings, radiographic features, neuroendoscopic management strategies, and histological findings are reported and discussed. METHODS: Since January 1990, 11 neuroendoscopic procedures were performed in 10 patients who harbored tectal tumors. The patients were followed for an average of 5 years (range 2 months-11 years), and a retrospective study was conducted in which case notes, radiological findings, operative notes, and histopathological findings were assessed. Magnetic resonance (MR) imaging was performed, and the images were used to classify patients into three groups: those with hypertrophy of the tectum in whom isointensity appeared on T1-weighted images (Group 1); those with a tectal tumor occupying the cerebral aqueduct in whom decreased signal intensity appeared on T1-weighted images, as well as no enhancement after gadolinium administration (Group 2); and those with a tectal tumor in whom mixed signal intensity and conspicuous evidence of contrast enhancement appeared on T1-weighted images (Group 3). The results of histological examination were consistent with MR imaging features: in Group 1, glial tissue or gliosis; in Group 2, benign astrocytoma; and in Group 3, malignant astrocytoma. Cerebrospinal fluid diversion was the only surgical treatment that provided relief from obstructive hydrocephalus. One patient in Group 3 underwent radiotherapy and subsequent partial tumor removal under neuroendoscopic guidance. Thereafter, the tumor remained in decline. All patients had normal intellectual status after undergoing surgery in which a neuroendoscope was used. CONCLUSIONS: Neuroendoscopic procedures can provide histological diagnosis, define the tumor-midbrain interrelationship, and be highly effective in treating obstructive hydrocephalus and in removing tectal tumors. This procedure may receive clinical application as a new management strategy for tectal glioma.     

Diploic epidermoid cyst: case report

We report the case of a diploic epidermoid cyst in the left front-parietal bone of a 70-year-old woman. A skull x-ray showed an osteolytic lesion with a sclerotic border, and CT scan revealed a low/iso-density mass and the destruction of both inner and outer tables. MRI showed hypo-intensity on T1-weighted image, hyper-intensity on T2-weighted imaging and remarkably-strong intensity on the diffusion-weighted imaging. Gadolinium enhancement was seen in the tumor capsule and dura of the peripheral tumor. In the operative view, most of the bone edge was regular with a sclerotic border, but an irregular section was present. The tumor adhered strongly to the dura mater and periosteum. The tumor was totally extirpated with the peripheral skull, dura mater and periost. On the postoperative MRI, gadolinium enhancement of the nearby dura mater and disappeared. We have added a discussion of the radiological features of diploic epidermoid cysts.     

Spontaneously ruptured craniopharyngioma cyst without meningitic symptoms --two case reports

Two cases of spontaneous rupture of cystic craniopharyngioma without chemical meningitis are described. A 70-year-old woman complained of headache and visual field disturbance in July 1993. The tumor was extirpated in November 1993 and again in December 1996. After regular periodic follow-up evaluation, she was hospitalized for reoperation because of expansion of the cyst on magnetic resonance (MR) imaging in November 1998. However, preoperative MR imaging taken 8 weeks later revealed spontaneous reduction of the cyst. A 69-year-old woman noticed deteriorating vision and bitemporal hemianopsia in November 1998. The tumor was removed in December 1998, and 50.4 Gy postoperative radiotherapy was administered. MR imaging in May 2000 demonstrated an enlargement of the cyst, so she was hospitalized again for operation. However, preoperative MR imaging taken 7 weeks later showed spontaneous reduction of the cyst. Neither of the cases of cyst rupture were accompanied by symptoms of chemical meningitis. The signal intensity of the tumors on T1-weighted MR imaging declined after cyst reduction. Thereafter, the cysts increased in size again at 7 months and 5 months. Regular follow-up on MR imaging is necessary, since the cyst size can increase rapidly, even after spontaneous rupture.     

Dural cyst at the foramen magnum

A 69-year-old male presented with a rare dural cyst manifesting as numbness and pain in the limbs. Magnetic resonance imaging revealed a mass anterior to the medulla oblongata appearing as low intensity on T(1)-weighted and high intensity on T(2)-weighted imaging, with no enhancement. A cystic lesion ventral to the medulla oblongata was removed via the lateral suboccipital transcondylar approach. Histological examination showed the wall of the cyst consisted of fibrous connective tissue with a dense zone and a loose zone, similar to the structure found in the dura mater. The lesion was diagnosed as dural cyst. Dural cysts can be defined as cyst with the wall consisting of dura mater-like fibrous tissue, and attached to the dura mater. The origin of the present dural cyst was considered to be congenital.