The journey of a floating fat: from suprasellar dermoid cyst to lateral ventricles

Excerpt

A 68-year-old man had a history of hypertension and retinal detachment in the left eye, occurred 3 years before that caused amaurosis. He presented with sudden nasal hemianopia in the right eye and tension-type headache mainly involving right frontal region, without head trauma. A CT-scan documented a hyperdense lesion in suprasellar cistern (Fig. 1a, b) with normal findings at intracranial angio-CT. Five days later, the hyperdense suprasellar lesion was no more visible at CT-scan, and MRI showed high-signal intensity foci within both lateral ventricles in T1, T2, and FLAIR sequences (Fig. 1c–f). Headache and visual symptoms gradually disappeared within 1 week. These findings were in keeping with the migration of floating fat droplets from a ruptured suprasellar dermoid cyst to lateral ventricles. Even though numerous reports of ruptured dermoid cysts exist, the presence of an intact cyst and the following migration of its content after rupture are poorly documented in literature. Dermoid cysts are intracranial tumors that may rarely appear hyperdense at CT-scan [1, 2], and fat droplets in the lateral ventricles are suggestive markers of their recent rupture [3]. Depending on the site, the rupture of the cyst may cause complications as, for example, acute hydrocephalus that should be ruled out particularly when the patient presents with new-onset headache. Traditional studies assert that cerebrospinal fluid (CSF) circulates from its production site in choroid plexuses, located in the inferior horn of the lateral ventricles, and flows via the foramina of Monro to third ventricle, aqueduct, and fourth ventricle towards central canal of spinal cord and subarachnoid spaces [4]. According to this model, the journey of fat droplets from suprasellar cistern would have occurred against CSF flow. Nevertheless, some recent studies [5‐7] have applied advanced MRI techniques, particularly inversion pulse [5] and improved motion-sensitized driven-equilibrium steady-state-free precession [6], to the study of CSF dynamics. Those studies have found that CSF motion is complex and irregular in physiologic conditions, resulting from a combination of unidirectional flow, pulsatile back and forth movements, and constant fluid exchange between CSF and interstitial spaces [7]. Thus, it is not surprising that fatty material, due to its relatively low specific weight, may be displaced in higher regions, like the frontal horns of lateral ventricles.

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