双语病例——皮样囊肿
朗读老师：Aimee 上海某医院
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History: A 57-year-old man presents with left facial numbness and decreased hearing on the left side for the past six weeks. Symptoms did not improve with antibiotics. The patient has a prior history of left pterional craniotomy.
MR images are shown below. Click to enlarge.
Findings
Brain MRI demonstrates a heterogeneous T1 hyperintense signal of the left cavernous sinus and Meckel’s cave. Diffusion-weighted imaging demonstrates restricted diffusion of the mass. Additional T1-weighted axial images show focal areas of increased signal along the left Sylvian fissure.
Differential diagnosis
Dermoid cyst
Lipoma
Craniopharyngioma
Teratoma
Metastasis
Meningioma
Diagnosis: Ruptured dermoid cyst
Key points
Dermoid and epidermoid cysts
Dermoid and epidermoid cysts account for less than 1% of intracranial masses.
Epidermoid cysts contain desquamated squamous epithelium. Dermoid cysts also contain sebaceous glands and hair follicles.
Epidermoid cysts follow cerebrospinal fluid (CSF) signal on all sequences except diffusion-weighted image. Epidermoid cysts restrict diffusion, while CSF does not.
The imaging appearance of ruptured dermoid cysts include disseminated foci of fat in the subarachnoid space, as in this case. Intraventricular rupture of cysts can lead to fat-fluid levels in the ventricular system.
The most common location of intracranial dermoid cyst is the sellar region.
The clinical presentation of ruptured dermoids is variable. The most common presenting signs and symptoms include headache, seizures, and hydrocephalus.
Ruptured dermoid cysts can cause chemical meningitis. Chemical meningitis may be indistinguishable from bacterial meningitis on CSF analysis and is managed with steroid therapy.
Ruptured dermoid cysts do not typically enhance. Leptomeningeal enhancement, however, may be present due to chemical meningitis.
Symptomatic dermoid cysts are managed with surgical excision. Recurrence may occur with incomplete excision, and there are rare reports of development of squamous cell carcinoma in remnants of dermoid cysts.
The prognosis is typically good, although chemical meningitis and seizures caused by rupture of intracranial dermoid cysts may cause significant morbidity and mortality.