2015 Volume 24 Issue 9 Pages 632-640
We report an extremely rare case of epidermoid cysts that appeared as multiple intracranial lesions on imaging, leading to aseptic meningitis, hydrocephalus, and malignant transformation.
A 67-year-old woman was hospitalized for investigation of headache, nausea, disorientation, and gait disturbance. Ventriculomegaly and the presence of two lesions were noted on CT : one was in the left cerebellopontine angle and the other in the left anterior horn of the lateral ventricle. Both were gadolinium-enhancing lesions on MRI. Cerebrospinal fluid examination revealed a mild increase of cells and protein, and the bacterial culture was negative. At first, a biopsy of the small intraventricular lesion was performed with neuroendoscopy, which was diagnosed pathologically as an epidermoid cyst. Placement of a ventricular peritoneal shunt improved the symptoms of aseptic meningitis and hydrocephalus. The main cerebellopontine angle lesion was monitored, but was resected 9 months later after growth had been noted. The diagnosis was squamous cell carcinoma. Despite radiation and chemotherapy, the disease progressed with intrathecal seeding and the prognosis was poor.
It was inferred that the spontaneous rupture of an epidermoid cyst in the ventral brainstem caused aseptic meningitis and non-obstructive hydrocephalus, and the cyst became malignant after repeated, chronic stimulation or inflammation. An epidermoid cyst with unusual features such as contrast effect, aseptic meningitis, hydrocephalus, or multiple lesions may indicate malignant transformation.