Asymptomatic spontaneous rupture of craniopharyngioma cyst.

Spontaneous rupture of craniopharyngioma cyst is a rare phenomenon. Either chemical meningitis or neurological improvement is usually associated with spontaneous cyst rupture. We experienced two patients who underwent asymptomatic spontaneous cyst rupture. MRI revealed reductions in the sizes of cysts in the left cerebellopontine cistern and middle fossa in a 4-year-old girl and a cyst in the suprasellar region of a 47-year-old man. These patients did not develop chemical meningitis, nor was there any change in neurological symptoms related to the craniopharyngioma cysts. According to our review of the literature, spontaneous rupture of craniopharyngioma cysts can be divided into three subtypes: (i) cyst rupture associated with chemical meningitis; (ii) cyst rupture with improvement in symptoms related to the craniopharyngioma and not associated with chemical meningitis; and (iii) asymptomatic rupture. It is important to be aware of unexpected cyst rupture during observation of craniopharyngiomas.