Endocrine Abstracts

Endocrine manifestations of arachnoid cysts, including suprasellar arachnoid cysts(SAC) are not well recognized. The effect of neurosurgical interventions on such manifestations is also not well reported. Here in we report a case of a young man with hypothalamic dysfunction secondary to SAC who made a good recovery after surgical treatment of the cyst.

A 22-yr-old man was referred to our endocrine clinic for evaluation of progressive weight loss and malaise. On examination the patient had a BMI of 12 kg/m², weighing 38.4 kg with normal development of secondary sexual characters and no abnormal endocrine signs. Investigations showed LH 3.2 (1–11 IU/l), FSH 4.1 (1–12 IU/l), prolactin 135 (50–360 mIU/l), testosterone 4.7 (10–35 nmol/l), TSH 2.0 (0.3–3.8 mIU/l), FT₃ 2.3 (3.3–6.5 pmol/l), SHBG 10 (10–70 nmol/l). A short synacthen test confirmed a functionally intact HPA axis: serum cortisol at baseline and 30 min measured 689 and 982 nmol/l respectively The results of combined provocative testing using TRH and GnRH stimulation were in keeping with hypothalamic dysfunction. An MRI scan demonstrated a 3 cm diameter cystic structure of the third ventricle resulting in hydrocephalus of the lateral ventricles. The cystic structure was compressing the hypothalamus, pushing the pituitary into the sella turcica. Subsequently, the patient was referred to neurosurgical team and he underwent endoscopic fenestration of the cyst. He had uneventful postoperative recovery. Histopathology confirmed the lesion to be an arachnoid cyst. Two months post-operatively, he noticed improvement in his energy level and weight. The serum levels of FT3 and testosterone measured 4.2 nmol/l and 12.0 nmol/l respectively; BMI increased to 18 kg/m². At six months and one year follow up the patient remained well with progressive weight gain.

Early recognition of endocrine manifestations of SAC may prevent the development of permanent hypopituitarism.