Endocrine Abstracts

Case History: 17 year old boy presented with a six week history of polyuria, polydipsia, headaches and easy fatiguability. Further investigations confirmed hypopituitarism with low early morning urine osmolality. MRI brain revealed soft tissue mass arising from tectal plate extending into cerebral aqueduct resulting in hydrocephalus with normal pituitary gland. Hydrocortisone, Levothyroxine and Desmopressin were started and urgent in-patient transfer to Neurosurgical unit in tertiary centre arranged.

Investigations: Na - 144 mmol/l (136-145), K – 4.2 mmol/l (3.5-5.1), creatinine – 90umol/l (62-106), calcium – 2.35 mmol/l (2.1-2.55), glucose – 2.5 mmol/l (3.0-6.0), HbA1C -30 mmol/mol, Free T4 – 9.7 pmol/l (12.6-21.0), TSH – 0.98 miu/l (0.51-4.3), prolactin – 838 mu/l (86-324), IGF-1 – 20.2 nmol/l (14.2-63.4), FSH – 1.8 iu/l, LH – 4.5 iu/l, 9 am cortisol – 179 nmol/l (133-537), urine osmolality – 123 mosm/kg (50-1400).

Management: Patient underwent endoscopic third ventriculostomy along with placement of Rackham reservoir and biopsy of the soft tissue mass simultaneously. Symptomatic improvement was noted and he was discharged home on adequate hormone replacement. Further MDT review with results of tumour biopsy has been arranged.

Conclusions: Tectal plate tumours can be a glioma, astrocytoma, medulloblastoma, germinoma, primitive Neuro-ectodermal tumour or metastasis. Thirty cases have been reported so far with 70-80% presenting with symptomatic obstructive hydrocephalus (by slowly plugging of the aqueduct of Sylvius). 25% had endocrinopathies mostly manifesting as precocious puberty, short stature or pan-hypopituitarism. Ventricular dilatation and increased intracranial pressure is hypothesized to be the cause for hypothalamic pituitary axis disturbance. Endoscopic ventriculostomy is preferred treatment of choice. Regular multidisciplinary follow up and monitoring is required to assess progress of the tumour and possible reversal of pituitary dysfunction when hydrocephalus has improved. Literature search reveals that this might be the first case of tectal plate tumour leading to hydrocephalus presenting as Diabetes Insipidus.