CASE 892 Published on 22.02.2001

Ruptured Intracranial Dermoid Cyst

Section

Neuroradiology

Case Type

Clinical Cases

Authors

S.W. Wallis, W.J.J. Van Roy, D. Wijnalda, R. Van Dijl

Patient

48 years, male

Categories
No Area of Interest ; Imaging Technique CT, MR, CT
Clinical History
Severe headaches and drowsiness. Normal physical and laboratory examinations.
Imaging Findings
Admitted to the neurology department because of severe headaches and drowsiness. Physical and laboratory examination revealed no abnormalities.
Discussion
Cerebral embryonic tumors (dermoids and epidermoids) are believed to arise from congenital rests of epithelial cells and skin tissue that remain in the intracranial cavity as a result of incomplete separation of the neuroectoderm from the cutaneous ectoderm at the time of closure of the neural tube. Intracranial dermoid tumors are less common than epidermoids. They account for less than 1% of all intracranial tumors. This rare congenital tumor occurs primarily extraaxial and in the midline, mostly in the pineal and suprasellar regions, as well as in the posterior fossa, either within the vermis or in the fourth ventricle. They may contain punctuate or rimlike calcifications. Symptoms from intracranial dermoids usually arise in the third decade of life. They may be the result of obstruction of the CSF pathways and consequent hydrocephalus or result of a so called chemical meningitis, from leakage of the contents of the cyst into the CSF. Patients with ruptured dermoid cyst may be rarely asymptomatic. The dermoid tumor has to be differentiated from an epidermoid. The location of epidermoids shows a much greater variation as well as a greater tendency to deviate from the midline. The most frequent site is the cerebellopontine angle, followed by the suprasellar region and the middle cranial fossa. Although epidermoids may present at any age, most are diagnosed during the fifth decade. Epidermoids in the cerebellopontine angle tend to present with cranial neuropathies, whereas suprasellar epidermoids present with hydrocephalus and middle cranial fossa epidermoids most frequently present with a chemical meningitis, secondary to leakage of tumor contents into the subarachnoidal space. The keratin, cholesterol and fat within these lesions give them a characteristic low density pattern on CT scan, very similar in density to the surrounding cerebrospinal fluid. Calcification and contrast enhancement are rare. A fat-fluid level within the subarachnoidal space or a ventricle, is highly suggestive for rupture of one of these tumors. On MR images, three signs may be seen: fat-fluid levels, wide sulci and subarachnoidal spread of fat deposits. The content of these cystic tumors, particularly the liquified cholesterol produces T1-shortening and resultant hyperintensity on SE T1-weighted images.
Differential Diagnosis List
Ruptured Intracranial Dermoid Cyst
Final Diagnosis
Ruptured Intracranial Dermoid Cyst
Case information
URL: https://eurorad.org/case/892
DOI: 10.1594/EURORAD/CASE.892
ISSN: 1563-4086