Introduction Sellar region cysts include Rathke's cleft cyst, cystic pi- tuitary adenoma, arachnoid cysts, dermoid/epidermoid cysts and cystic craniopharyngioma. A cyst in the in- fundibulum is extremely rare [1]. Spontaneous regres- sion of a pituitary cyst has been reported [2], but not of an infundibular cyst. Case report A 74-year-old man was admitted with a 1-month history of head- aches and intermittent blurred vision. There was no history of sys- temic disease, and examination was normal. MRI at 1.0 T showed an enlarged, oval pituitary stalk reaching 9 mm in width (Fig. 1). The stalk was isointense on T 1-weighted images and gave low sig- nal relative to the cortex on T 2 weighting. The signal intensity did not correspond to any stage of haemorrhage. A very small ante- rosuperior part of the stalk showed linear contrast enhancement, suggesting that the lesion originated from the posterior part of the infundibulum. The entire length of the stalk was clearly seen. The thickened stalk was not compressing the optic pathways or the pi- tuitary gland. The pituitary gland, medial eminence and tuber ci- nereum were normal in size and shape. The other parts of the brain showed no abnormality. The patient underwent detailed investigation to ascertain the nature of the mass. No calcification was seen on CT. Cerebrospinal fluid (CSF) analysis, plasma and urinary osmolarities before and after water deprivation, pituitary hormone profile including growth hormone, prolactin, luteinizing hormone, follicle-stimulat- ing hormone, thyrotropin, cortisol and free T 4 were all normal with no clinical evidence of hormonal imbalance. Thoracic and abdominal CT showed no pathology. MRI was repeated 4 months after presentation; there had been no change. The hormone profile was repeated and was again nor- mal. The patient was taking only simple analgesics. On MRI 1 year later, the stalk was seen to have returned to its normal size and configuration (Fig. 2). Neuroradiology (2000) 42: 357±359 Ó Springer-Verlag 2000 DIAGNOSTIC NEURORADIOLOGY N. Kocer S. Kurugoglu F.Kantarci M. Cantasdemir N. Gazioglu C. Islak Spontaneously regressing infundibular cyst: a case report Received: 1 February 1999 Accepted: 2 August 1999 N. Kocer ( ) ) × S. Kurugoglu × F.Kantarci × M. Cantasdemir × C. Islak Istanbul University, Cerraphasa Medical Faculty, Neuroardiology Section, Department of Radiology, 34300 Istanbul, Turkey e-mail: nkocer@istanbul.edu.tr Tel.: + 90-2 12-5 86 15 86 Fax: + 90-2 12-5 86 15 86 N. Gazioglu Istanbul University, Cerraphasa Medical Faculty, Department of Neurosurgery, Istanbul, Turkey Abstract A 74-year-old man re- ported headaches and blurring of vision for 1 month. MRI showed a nonenhancing infundibular cyst. Neurologic findings, blood and cerebrospinal fluid examinations, and chest and abdominal CT were all normal. MRI 4 months later showed no change. The patient was without any medication other than simple analgesics. One year later, the stalk had returned to its normal size and configuration on MRI. Key words Stalk, pituitary × Cyst, infundibular × Magnetic resonance imaging