Expanding experience with spontaneous dermoid rupture in the MRI era: diagnosis and follow-up.

With widespread use of CT and MR imaging, experience with spontaneous dermoid rupture has significantly increased. What was previously believed to be a generally severe or even fatal accident, being the diagnosis made either at surgery or autopsy, or in patients with such consequent conditions as chemical meningitis or obstructive hydrocephalus, now appears to be more frequent than previously thought, and there is some evidence that it may also cause only a slight symptomatology or even be quite asymptomatic. We reviewed the clinical and imaging data of our series of five patients with spontaneously ruptured dermoids, spinal in one case, and intracranial supratentorial in four. These had their diagnosis following mild symptoms (number two cases) or incidentally (number two cases); the spinal tumor caused acute bladder dysfunction, possibly while undergoing rupture, and was associated with indolent intracranial fat spread. Three of the patients also had MR demonstration of asymptomatic persistance of fat spread in the subarachnoid spaces, respectively, 3, 4, and 5 years after rupture. One of the five cases, concerning a parasellar dermoid followed up over 6 years, provides the first demonstration of MR signal intensity change of the tumor prior to rupture.