A 39-year-old woman with sudden severe headache, vertigo, and nausea
A
B
C
D
What is your diagnosis?
The answer is Ruptured Dermoid Cyst
Dermoid cysts arise from the inclusion of cutaneous ectodermal cells during neural tube closure in embryogenesis.
The cyst may contain fat, which is typically hyperintense on T1WI (arrow in A) and suppressed by fat-saturation T1WI (arrow in B).
Dermoid cysts are usually asymptomatic until rupture, resulting in the release of fat droplets into the ventricles or subarachnoid space.
In our case, this is seen as high signal in the frontal horns on T1WI (yellow arrows).
A chemical shift artifact along the frequency encoding direction (antero-posterior) at the interface of fat and CSF can be seen as a dark line on T2WI (green arrows).
An acute chemical meningitis may result, most commonly with symptoms of seizures or headaches.
中文版：
女性，39歲，突發劇烈頭痛，眩暈，嘔吐。
診斷：皮樣囊腫破裂
在胚胎發育，神經管閉合過程中，皮樣囊腫起源於外胚層細胞。
囊腫內可含有脂肪，T1WI表現為高信號（A圖箭頭），T1WI脂肪抑制序列表現為低信號（B圖箭頭）。
皮樣囊腫未破裂時通常無臨床症狀，破裂後，囊內脂肪滴溢出，並流入腦室及蛛網膜下腔。
本病例中，雙側腦室額角內可見T1WI高信號（黃箭頭）。
脂肪與腦脊液交界區可見沿頻率編碼方向（前後方向）的化學位移偽影，表現為T2WI線樣低信號（綠色箭頭）。
最常見症狀為急性化學性腦膜炎引起的癲癇或頭痛。