Intracranial dermoid cyst
Updates to Article Attributes
Intracranial dermoid cysts are uncommon lesions with characteristic imaging appearances. They can be thought of as along the spectrum from epidermoid cysts at one end (containing only desquamated squamous epithelium) and teratomas at the other (containing essentially any kind of tissue from all three embryonic tissue layers).
Epidemiology
Dermoid cysts account for approximately 0.5% of all primary intracranial tumours, and are a little more commonly found in females 6. Typically dermoid cysts present in the first three decades of life 6.
Clinical presentation
Many intracranial dermoid cysts are asymptomatic, and are only found incidentally. Often there is a long history of vague symptoms, with headache being a prominent feature 4. Symptomatic clinical presentation usually occurs in one of two ways:
- mass effect
- compression of adjacent structures, e.g. optic chiasm
- rupture (spontaneous, traumatic, or iatrogenic (at resection))
- leakage of sebum into the subarachnoid space
- results in an aseptic chemical meningitis
- presentation is variable, ranging form headache, to seizures, vasospasm and even death 4
Pathology
Dermoid cysts are thought to occur as a developmental anomaly in which embryonic ectoderm is trapped in the closing neural tube between the 5th-6th weeks of gestation.
Dermoid cysts, like epidermoid cysts are lined by stratified squamous epithelium. Unlike epidermoid cysts however they also have epidermal appendages such as hair follicles, sweat and sebaceous glands. The later is responsible for the secretion of sebum which imparts the characteristic appearance of these lesions on CT and MRI.
A common misconception is that dermoid cysts contain adipose tissue. This is not the case, as lipocytes are mesodermal in origin and dermoid cysts (by definition) are purely ectodermal. A dermoid cyst with adipose tissue would be a teratoma.
Radiographic features
Intracranial dermoid cysts are typically located in the midline, although they can grow towards one side or the other. Locations include:
-
posterior fossa
/ vermis/vermis - suprasellar
/ subfrontal/subfrontal
It is interesting to note that publications vary as in what is the most common location of dermoid cysts 6-7.
Plain film
Historically, when skull x-rays were routinely used in the assessment of suspected intracranial pathology, a focal lucency due to the fatty sebum 5.
CT brain
Typically dermoid cysts appear as well defined low attenuating (fat density) lobulated masses. Calcifications may be present in the wall. Enhancement is uncommon, and if present should at most be a thin peripheral rim.
Very rarely they demonstrate hyperdensity thought to be due to a combination of saponificaiton, microcalcification and blood products. This is usually the case when present in the posterior fossa, although why this is the case is not certain 4.
MRI brain
Unlike intracranial lipomas which follow fat density on all sequences, intracranial dermoids have more variable signal characteristics 1-4:
-
T1
- typically hyperintense (due to cholesterol components)
- droplets in the subarachnoid space may be visible if rupture has occurred
-
T1 C+ (Gd):
-typically do not enhance -
T2:
-variable signal ranging from hypo to hyper intense
Treatment and prognosis
Dermoid cysts when symptomatic can be surgically excised and provided complete excision is achieved recurrence is uncommon. Sometimes due to local adhesion of the capsule to vital structures, incomplete excision must be performed. Recurrent growth in either case is slow 7.
Differential diagnosis
The differential is limited to pituitary region lesions with intrinsic high T1 signal or to even a smaller list (as CT and fat suppressed sequences are often available) of lesions which contain fat:
- intracranial lipoma
-
intracranial teratoma
-: immature
-<p><strong>Intracranial dermoid cysts</strong> are uncommon lesions with characteristic imaging appearances. They can be thought of as along the spectrum from <a href="/articles/epidermoid-cyst">epidermoid cysts</a> at one end (containing only desquamated squamous epithelium) and <a href="/articles/intracranial-teratoma">teratomas</a> at the other (containing essentially any kind of tissue from all three embryonic tissue layers). </p><h4>Epidemiology</h4><p>Dermoid cysts account for approximately 0.5 % of all primary intracranial tumours, and are a little more commonly found in females <sup>6</sup>. Typically dermoid cysts present in the first three decades of life <sup>6</sup>. </p><h4>Clinical presentation</h4><p>Many intracranial dermoid cysts are asymptomatic, and are only found incidentally. Often there is a long history of vague symptoms, with headache being a prominent feature <sup>4</sup>. Symptomatic clinical presentation usually occurs in one of two ways: </p><ol>-<li>mass effect<ul><li>compression of adjacent structures e.g. optic chiasm</li></ul>- +<p><strong>Intracranial dermoid cysts</strong> are uncommon lesions with characteristic imaging appearances. They can be thought of as along the spectrum from <a href="/articles/epidermoid-cyst">epidermoid cysts</a> at one end (containing only desquamated squamous epithelium) and <a href="/articles/intracranial-teratoma">teratomas</a> at the other (containing essentially any kind of tissue from all three embryonic tissue layers). </p><h4>Epidemiology</h4><p>Dermoid cysts account for approximately 0.5% of all primary intracranial tumours, and are a little more commonly found in females <sup>6</sup>. Typically dermoid cysts present in the first three decades of life <sup>6</sup>. </p><h4>Clinical presentation</h4><p>Many intracranial dermoid cysts are asymptomatic, and are only found incidentally. Often there is a long history of vague symptoms, with headache being a prominent feature <sup>4</sup>. Symptomatic clinical presentation usually occurs in one of two ways: </p><ol>
- +<li>mass effect<ul><li>compression of adjacent structures, e.g. optic chiasm</li></ul>
-<a title="Posterior cranial fossa" href="/articles/posterior-cranial-fossa">posterior fossa</a> / vermis</li>-<li>suprasellar / subfrontal</li>- +<a href="/articles/posterior-cranial-fossa">posterior fossa</a>/vermis</li>
- +<li>suprasellar/subfrontal</li>
-<strong>T1 C+ (Gd)</strong> - typically do not enhance</li>- +<strong>T1 C+ (Gd):</strong> typically do not enhance</li>
-<strong>T2</strong> - variable signal ranging from hypo to hyper intense </li>- +<strong>T2:</strong> variable signal ranging from hypo to hyper intense </li>
-<li><a href="/articles/intracranial_lipoma">intracranial lipoma</a></li>- +<li><a href="/articles/intracranial-lipoma">intracranial lipoma</a></li>
-<a href="/articles/intracranial-teratoma">intracranial teratoma</a> - immature</li>- +<a href="/articles/intracranial-teratoma">intracranial teratoma</a>: immature</li>
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