Ruptured dermoid cyst consisting of two adjacent masses with different components in the middle and posterior cranial fossa

Abstract Background Intracranial dermoid cysts are among the rarest tumors, and cases of rupture are even rarer. Dermoid cysts present great variety of radiographic features depending on their origin, which may make the diagnosis difficult. Case description A 17-year-old female complained of headache and nausea. Magnetic resonance imaging (MRI) showed two masses in the right middle cranial fossa and in the posterior fossa, which had different components according to their locations. Additionally, we observed fatty droplets in the subarachnoid space on MRI. We resected the tumor, and the postoperative diagnosis was ruptured dermoid cyst. There was continuity between both masses, indicating these were from the same tumor. Conclusion We experienced a rare case of ruptured dermoid cyst which presented as two adjacent lesions in the middle cranial fossa and posterior cranial fossa. The main components of the tumor were significantly heterogeneous depending on the lesion site.