Spontaneous regression of an epidermoid cyst of the cavernous sinus.

Epidermoid cysts are rare lesions in the pediatric population. The natural history of epidermoids is usually that of slow growth, although rupture and cases of malignant transformation have been reported. Spontaneous regression of an intracranial epidermoid cyst has not previously been described to our knowledge. We present a 3-year-old boy who presented with severe vertigo. MRI was performed which revealed a 2cm non-enhancing lesion in the right cavernous sinus. The lesion was T1-hypoinsense, T2-hyperintense, and with evidence of restricted diffusion, consistent with an epidermoid cyst. The patient was followed with annual MRI studies over the next 3years, demonstrating progressive reduction in the size of the lesion over time, with complete resolution after 3years. The child's symptoms also resolved during this period. Long-term follow-up imaging at 5years showed no evident lesion. To our knowledge, this is the first report documenting spontaneous regression of an intracranial epidermoid cyst. While isolated, this finding demonstrates the potential for involution of epidermoids and lends support to the clinical practice of careful observation of these lesions, especially when located in areas associated with high potential surgical morbidity. Importantly, the novelty of this observation suggests a need for further study to better elucidate the underlying mechanism of this regression.