25 y.o. woman with a two day history of painful and swollen right eye. Brought in by her spouse, she denies any history of trauma.
Periorbital edema and erythema around the right eye and orbit.
â€¢ Mixed signal intensity mass, probably arising from the right orbital roof.
â€¢ The lesion has some small areas - some linear - of T1-shortening suggestive of blood products or perhaps lipid material.
â€¢ There is faint peripheral rim enhancement, that may be in the surrounding tissue, or a rim of this lesion.
â€¢ No internal contrast enhancement
â€¢ Subacute blood products - hematoma
â€¢ Atypical Lipoma
â€¢ Epidermoid tumor
â€¢ Dermoid cyst
â€¢ Mucocele of frontal sinus
â€¢ Metastatic disease
Due to the presentation of this patient with acute onset of periorbital swelling and edema; and, with the MRI findings - spouse abuse was as a diagnositic consideration. In this clinical context, the MRI findings were consistent with subacute or chronic hematoma.
Dermoid cysts are believed to arise from congenital rests of epithelial cells and skin tissue that become incorporated into the intracranial cavity as a result of incomplete separation of the neuroectoderm from the cutaneous ectoderm at the time of neural tube closure. They are likely to present as midline masses (as opposed to epidermoids), mostly in the retroclival and suprasellar regions, due to an earlier inclusion of ectoderm into the neural tube. They may contain ectodermal glands such as apocrine glands and hair follicles. Teeth may also be found - altough rarely.
They are rare neoplasms as they account for less than 1% of all intracranial tumors. The slow growth rate of dermoids delays the clinical presentation until the 3rd or 4th decade of life. The clinical presentation is variable and nonspecific. Headache, seizures and dementia have been described. A ruptured cyst may present as chemical meningitis from leakage of cystic contents into the CSF. Rarely patients with ruptured dermoid cyst may be asymptomatic.
MR findings of dermoid tumors include heterogeneous mass usually at the midline. Sometimes fluid- fluid levels are observed. The lesion appears hyperintense on T1W imaging while on fat suppressed T1W imaging the mass loses signal. The dermoid tumor may 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 for epidermoid 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.
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