Rathke's cleft cyst with non-hemorrhagic rupture resulting in alteration of signal intensity for a short period: a case report

In a case of 23-year-old female with Rathke's cleft cyst (RCC), unusual changes with size and morphology on computed tomography (CT) and magnetic resonance images (MRI) were noted in a short period of 3 weeks after spontaneous rupture. The CT noted that the intracystic isodensity was changed to hyperdensity. And MRI showed not only a decrease in size of the lesion but also changing from hypo- and hyperintensity in T1- and T2-weighted images to hyperintensity in both T1- and T2-weighted images. The intraoperative findings disclosed that the cyst content was milky-like, but not hemorrhagic. We considered that the leakage of cyst content to the cerebrospinal fluid pathway caused not only inflammatory reaction but also waxing and waning of both the cyst size and intralesional protein concentration, which resulted in unusual changing CT and MR appearance. We should take into consideration that the nature of RCC can be altered by not only intracystic hemorrhage but also non-hemorrhagic rupture even for a short period.