PT Cheung, W Lam, RKP Wong, E Kwan, L Low, SY Ha

Aim To compare the MR changes in the hypothalmo-pituitary region in LCH patients with or without pituitary hormone deficiency.

Method and Materials Patients (established or newly diagnosed) with biopsy proven LCH were prospectively recruited for the current study. MR brain was performed. Magnevist 0.2 ml/kg) was given intravenously by manual push followed by fast gradient echo (FSPGR) examination of 30 frames over 111 seconds. The dynamic course of contrast enhancement were followed by measuring the mean pixel density of the structures of interest That of the straight sinus was used as a reference point. Non-LCH patients who had undergone similar study were included as controls. Urinary concentration test was performed in all whilst other endocrinological workup were performed as clinically indicated.

Results Six out of the 10 studied LCH patients (7 months to 15 years old) had endocrinopathies and MR changes including absent posterior pituitary hyperintense signal (6/6) and thickened pituitary stalk (3/6). Four of them had delayed contrast enhancement of the pituitary gland. Only one patient had both thickened stalk and delayed contrast enhancement. One had atrophic pituitary gland and stalk while another had a contrast enhancing hypothalamic mass. All had diabetes insipidus (5 complete and 1 partial) while the one with atrophic pituitary had panhypopituitarism and another two had growth hormone deficiency. The four LCH patients without endocrinopathy had normal MR study. Nine patients without LCH (but with or suspected to have other intracranial pathologies) had normal pituitary stalk and no delay in contrast enhancement on dynamic study.

Conclusion All six patients with pituitary hormone deficiency have MR changes in contrast to none in those without. The most consistent MR feature is the absence of posterior pituitary hyperintense signal, which is, however also seen in occasional normal subjects and therefore not specific. Both the presence of thickened pituitary stalk and delayed contrast enhancement are more specifically associated with endocrinological manifestation in LCH. The dynamic study may therefore offer additional evidence of hypothalmo-pituitary involvement in LCH Longitudinal study of newly diagnosed LCH patients with/without DI would be necessary to clarify whether such MR changes can predict subsequent development of endocrinopathy.