Suprasellar Mature Teratoma/Dermoid Cyst with the Poké Ball Sign

Brain magnetic resonance imaging (MRI) revealed a well-defined suprasellar cystic lesion, with internal fat-fluid level, presenting hyperintense signal in its upper aspect, due to fat, low signal in its lower portion, due to fluid, and a floating round structure with isointense signal in the central region, on T1-weighted imaging, without gadolinium enhancement (Figure 1). The central floating round component usually is composed of multiple spherules of fibrin, keratin, fat, sebum, and hair.3 To the best of our knowledge, this sign has not yet been described in intracranial mature teratomas/dermoid cysts, although it is well described in the ovaries. MRI accurately evaluates the topography, size, structures involved by the lesion and estimates the extent of resection, allowing an appropriate surgical approach and early diagnosis.6 This is important because one possible complication of a dermoid cyst is rupture, in which fat droplets spread out into the subarachnoid space, causing chemical meningitis.7 Thus, an early diagnosis may prevent this complication and assist in the proper surgical planning, reducing the risk of intraoperative rupture. [...]the “Poké Ball sign” is very illustrative of the importance of imaging in diagnosis and surgical planning in these cases, by directly suggesting a histological diagnosis.