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Case 2

40 year old man presenting with headache

Dermoid

Congenital ectodermal inclusion cyst containing dermal appendages

Well-circumscribed lipid containing mass

Location

MC: Sellar/Parasellar/Frontonasal region

Posterior fossa: midline vermis & 4th vent

Intraventricular: assoc/w tela choroidea

Size: Variable

May Rupture: Fat droplets in cisterns, sulci & vents

Dermoid

MR findings

T1WI

Hyperintense (fat content)

May be mixed with lower intensity due to proteinaceous content

Fat-fluid level in cyst/ventricles (ruptured)

T2WI:

Heterogeneous: hypo- to hyperintense

Chemical shift in freq encoding direction on long TR

Hair elements may be hypointense

Dermoid

T1+C

Uncomplicated cyst does not enhance

Margins may enhance due to displaced vascular structures or reactive fibrosis

Enhancement within cyst suggests superimposed infection and raises question of dermal sinus tract.

Rupture may result in chemical meningitis

Dermoid

Demographics

30 – 50 years old

Slight male predilection

Rare tumor <0.5% of primary intracranial tumors

Pathology

Unilocular cyst with thick wall of connective tissue

Contents: Lipid & Cholesterol debris; possibly with hair, bone or cartilage.

Rare SCCa degeneration in surgical remnant *