Unusual changing CT and MR appearance of an epithelial intracranial cyst

Introduction: Epithelial cysts are infrequent intracranial lesions and may content cilia and mucosecretant cells that may be responsible for the protein concentration within the contents and the variable radiological appearance on CT and MRI. Methods and patients: We present a case of an extraaxial epithelial cyst with changing CT and MR characteristics. Results: The appearance of our cyst on CT or MRI changed with size and morphology. When CT studies showed an hypodense cyst, the lesion was large but when an hyperdense mass was present, the lesion was smaller. In the later situation MRI showed hyperintensity on T1-weighted images and hypointensity on T2-weighted images and the protein concentration of the cystic contents was high. Conclusions: We believe that a relatively high protein concentration in our cyst was the major factor for the high attenuation on CT and the hyperintensity or hypointensity on T1- and T2-weighted images, respectively. We believe than these atypical imaging findings were caused by changes in the protein concentration within the cyst.     

CT and MR appearance of multiple intracranial lesions associated with suprasellar dermoid cyst

Multiple lesions associated with suprasellar dermoid cyst are well demonstrated preoperatively on computed tomography (CT) and magnetic resonance (MR) imaging. Although the presence of multiple fatty globules in ventricles and/or subarachnoid space has been thought to be evidence of ruptured dermoid cyst, there are no signs or symptoms, including operative findings, attributable to dermoid cyst rupture in our case. The distinctive CT and MR appearance is described and possible etiology of the multiple lesions is discussed.     

Unusual presentation of a dermoid cyst in the ischiorectal fossa. Magnetic resonance imaging and ultrasound appearances

The ischiorectal fossa may give rise to a wide variety of pathological entities, although it is composed of relatively few structures. Developmental cysts are included among the list. Large epidermoid cysts in the ischiorectal fossa have been previously described (Fujimoto et al., Clin Imaging 17:146–148, 1993; Ng et al., Can J Surg 49:435–436, 2006). However, to the best of our knowledge, there is no published case in the English literature of a dermoid cyst within the ischiorectal fossa. Using magnetic resonance (MR) imaging and a subsequent ultrasound-guided biopsy, we were able to offer a focused differential that included a dermoid cyst within the ischiorectal fossa in a 55-year-old man presenting with a painful mass on the buttocks. Hair and fatty components were obtained by targeted ultrasound-guided biopsy. On MR imaging, the mass was seen to be well circumscribed and registered a heterogeneous T1-weighted signal that corresponded to layers of fat and debris on short-tau inversion recovery (STIR) imaging. A well-defined ball of fat was noted centrally within the lesion, with a speckled low T1 and low T2 signal within it. Hair admixed with fat was obtained from it by targeted ultrasound-guided biopsy. There was no enhancement of the lesion after administration of gadolinium. On ultrasound, the lesion was well circumscribed and heterogeneous; the echogenic area corresponded to the fat signal seen on magnetic resonance imaging (MRI). The lower level echoes within the lesion corresponded to the debris seen on MRI. The central rounded area of speckling, registering fine posterior shadowing corresponded to the hairy contents obtained by the targeted ultrasound-guided biopsy. A differential diagnosis of all lipomatous lesions was included in the pre-biopsy report: fat necrosis within a lipoma; well-differentiated liposarcoma; myxoid liposarcoma and dermoid cyst. Histopathological diagnosis following complete surgical resection was that of a dermoid cyst.     

Intracerebral extension of nasal dermoid cyst: CT appearance

We report on a 46-year-old man with a congenital nasal dermoid cyst that extended intracranially to form large bifrontal intraaxial dermoid cysts, which became secondarily infected through a nasal dermal sinus tract. Computed tomography demonstrated bilateral frontal lobe ring enhancing cystic masses containing fat-fluid levels consistent with dermoid cyst abscesses. Axial and coronal CT of the skull base and nose demonstrated a midline bony canal extending from two dimples on the dorsum of the patient's nose to the base of the anterior cranial fossa. The clinical, CT, and surgical findings are reviewed as well as the embryogenesis of congenital nasal dermoid cysts.     

Spontaneous rupture of intracranial dermoid cyst. Clinical and radiological study

A 22 year old woman had a seizure, and the skull X-ray showed an intracranial arched calcification. CT scan permitted diagnosis of dermoid cyst. Rupture of the cyst was testified by low density areas disseminated on the cortical surface and intra-ventricular fat level. Surgical removal confirmed dermoid cyst with rupture and fat fluid inside. Authors underline infrequency of such intra-ventricular fat level. CT scan, with low density of lipidic origin promote considerably such diagnosis both of the real nature of the cyst and of its rupture.     

Tetraventricular hydrocephalus due to ruptured intracranial dermoid cyst

We present the MR imaging findings in a patient who developed tetraventricular hydrocephalus after massive rupture of dermoid cysts with generalized subarachnoid and ventricular spread of cyst contents. The development of tetraventricular hydrocephalus due to ruptured dermoid is a very unusual complication, and was attributed to cyst contents interfering with passage of cerebrospinal fluid through the arachnoid granulations and fourth ventricular outlet foramina. Received: 31 January 2000; Revised: 3 March 2000; Accepted: 16 March 2000     

Unusual appearance of a cisternal hydatid cyst

We herein describe a case of an isolated multilocular hydatid cyst occurring in the basilar cisterns, with nondependent levels of different signal intensities shown on MR images. Three portions were visualized on T1-weighted images: the hyperintense inferior aspect, the isointense central part, and the superior aspect of lower signal intensity. The inferior portion was hypointense on T2-weighted images. This unusual appearance was caused by layering of hydatid sand and may represent a characteristic feature of hydatid disease.     

Ruptured spinal dermoid cyst with disseminated intracranial fat droplets

Fat droplets in the cerebrospinal fluid (CSF) is a well-known complication of ruptured intracranial dermoid tumours. We report an unusual case of a ruptured spinal dermoid tumour. MR images showed a tethered spinal cord and an intramedullary fat-containing mass. Fat droplets were revealed in the ventricles and the cisternal spaces on brain CT and brain MR. In the English literature, a ruptured spinal dermoid tumour accompanying a tethered spinal cord is extremely rare.     

Unusual CT features of dermoid cyst in the posterior fossa

A dermoid cyst of the posterior fossa in a 73-year-old man is reported. The presentation of the cyst was unusual because of the age of the patient, the spontaneously hyperdense aspect of the mass on CT, the partial rim enhancement of the lesion, and the presence of perilesional edema. On pathologic examination, the cyst contained small amount of fat, hairs, necrosis, and small areas of hemorrhage. The amount of hemorrhage found could not explain the spontaneous hyperdensity of the lesion found on CT. The hyperdensity may be related to high protein content of the lesion. Electronic Publication     

Three-dimensional chemical shift-selective MRI of a ruptured intracranial dermoid cyst

We report a man with a ruptured intracranial dermoid cyst, suffering from headache, nausea, vomiting and a generalised seizure. MRI was performed before and 2 weeks after surgical resection. On T1-weighted images the tumour gave high signal, as did fatty material in the frontal and parietal brain sulci. Identification of this hyperintense material as lipids was possible by chemical-shift-selective 3 D gradient-echo imaging, which provided excellent contrast between the subarachnoid lipids and the adjacent normal brain, with a good spatial resolution. Possible complications of subarachnoid and intraventricular lipid particles after dermoid cyst rupture are discussed and the diagnostic value of 3 D chemical-shift-selective additional to conventional T1-weighted spin-echo images in identification of even small amounts of fat is emphasised.     

Unusual appearance of thromboembolism on perfusion lung imaging.

A 46-year-old woman with advanced ovarian carcinoma had progressive dyspnea and was evaluated with ventilation and perfusion lung imaging. A characteristic pattern of multiple branching perfusion defects of a segmental nature on the perfusion scan suggested tumor microembolism and lymphangitic carcinomatosis. However, in this case, this pattern was associated with pulmonary thromboembolism and was documented by the post mortem examination. Pulmonary thromboembolism should be included among the differential diagnoses in a patient with clinical symptoms and a perfusion scan that reveals multiple branching perfusion defects.     

Diagnosis of ruptured intracranial dermoid cyst: value MR over CT

The CT and MR findings of seven patients with pathologically proved ruptured dermoid cysts were reviewed to analyze the MR characteristics and to see if MR evaluation had significant advantages over CT. In six cases, both CT and MR identified fatty material in the CSF spaces. Hemorrhage complicated preoperative diagnosis in one case. Patterns of extraaxial fat distribution were as follows: intraventricular fat/CSF levels (three patients), generalized subarachnoid spread (six patients), and localized subarachnoid spread with sulcal widening (one patient). There was no correlation between fat distribution and clinical symptoms. MR showed the vascular involvement better than CT did in five of seven cases, and showed extension of the cysts into the skull base in two cases. Signal intensity of the solid mass was low on T1-weighted MR images and inhomogeneously high on T2-weighted images, which correlated pathologically with the presence of crystal cholesterol, hair, sebaceous glands, and epithelial cells in all cases. On MR, brain parenchyma showed little edema or other reaction to the masses, which were typically large. The value of MR over CT in the examination of ruptured dermoid cysts is the conspicuity of the extent of subarachnoid spread, involvement of the extraaxial structures, and evidence of vascular compromise, which can obviate angiography. MR had no advantage over CT in making the initial diagnosis of ruptured dermoid, but it would be the preferred preoperative study.     

Unusual location of an intracranial chondroma.

We describe the MR findings in a case of chondroma arising from the falx. At MR imaging, the mass appeared well defined, lobulated, hypointense to isointense on T1-weighted images, and very heterogeneous with marked hyperintense areas on T2-weighted images. After contrast administration, this tumor enhanced slightly on delayed images.     

颅内巨大皮样囊肿合并自发破裂1例

患者男,71岁。头部外伤后发现颅内占位8年余,右下肢无力2年余。8年前头部外伤后头颅CT检查发现颅内占位,元明显不适症状,未继续诊治。入院前2年开始自觉右下肢无力,活动不灵,走路拖行。查体：神志清楚,右上肢可见震颤,右下肢肌力Ⅳ级,病理征未引出,膝腱反射正常。     

额顶部头皮下皮样囊肿1例

患者男,25岁.出生后发现额顶部头皮下有一黄豆大小肿块,缓慢增大,近3个月以来增大明显,遂入院.体检:额顶部半球形包块呈蕈样突出,约5cm,表面光滑,有囊性感,基底部不活动.头颅X线片示:额顶部见弧形压迹,局部颅外板变薄,稍内陷,颅内板无异常(图1).MRI平扫示:额顶部皮下1个类圆形肿块向外突起,大小约3.0cm×4.5cm×6.0cm,边界清楚,T1WI、T2WI均呈高信号并见分层现象(图2),压脂后信号减低,病灶前底部见小团状低信号区,局部颅板吸收变薄下陷,肿块与颅内无连通.MRI诊断:额顶部皮下囊性肿块,考虑:①皮样囊肿;②胆脂瘤.