Expanding cerebrospinal fluid cyst in the operative cavity: an unusual postoperative complication.

We present two cases of expanding cerebrospinal fluid (CSF) cyst formation appearing as a local complication after supratentorial craniotomy for complete brain tumour removal. Surgical treatment was simple and effective. Diagnosis was less obvious due to apparently normal radiological patterns and the absence of an expanding mass. CSF cysts should be included in the differential diagnosis of postoperative complications, particularly when neuroradiographic findings are inconclusive.