[Abscess formation in a Rathke's cleft cyst].

A 66-year-old woman with a diagnosis of asymptomatic Rathke's cleft cyst had been observed for almost 2 years and was admitted to our hospital in June 1992 because of high fever and loss of consciousness. Ophthalmological examination revealed right Horner's sign and ophthalmoplegia. A tentative diagnosis of bacterial meningitis was made based on the results of a lumbar puncture. T1-weight MRI showed a marked increase in the size of the suprasellar cystic mass lesion compared to the MRI images obtained 2 years earlier. Hence, the preoperative diagnosis was pituitary abscess. Both transsphenoidal and nasal drainage of the abscess were performed. The pathological findings were consistent with a Rathke's cleft cyst and showed chronic inflammatory cells. The postoperative course was uneventful and the patients eye movements recovered completely. The possible mechanisms of abscess formation in Rathke's cleft cyst are discussed.