LAUSR

Background Colloid cysts are rare developmental lesions, accounting for approximately 1% of intracranial tumors. Often, these benign lesions are asymptomatic, but they are associated with significant mortality as a result of acute hydrocephalus. This mortality in patients with vague or no symptoms dictates a need for better understanding of the etiology of colloid cysts to expedite diagnosis and management. We present a case of monozygotic twins with colloid cysts to propose a genetic etiology for colloid cyst. Case Description Previously healthy male monozygotic twins presented 4 years apart with headache secondary to hydrocephalus as a result of colloid cysts. Both patients underwent multiple surgeries and were doing well at last follow-up. Conclusions The present case adds to a body of literature of familial colloid cysts, suggesting higher concordance in monozygotic compared with dizygotic twins. This may be due to high genetic load, shared intrauterine environment, epigenetic changes, or genetic mutation. This literature review suggests that given high morbidity and mortality of colloid cysts, screening may be beneficial. Even in the absence of a single, definitive genetic etiology, we recommend consideration of genetic screening or, at a minimum, screening with neuroimaging for monozygotic twins in cases where 1 twin is diagnosed with colloid cyst.