ESPE Abstracts

Aim: To highlight the role of in-vivo magnetic resonance spectroscopy (MRS), as a non-invasive tool that can clarify the specific etiology of a sellar tumour in a boy with precocious puberty.

Case presentation: A 4-year-old boy was admitted due to repeated episodes of focal seizures with fixed gaze, head turn to the right, and postictal drowsiness. Parents reported episodes of inappropriate laughter ("gelastic seizures") in the previous year. The child was referred to the endocrine department for investigation of possible precocious puberty. Clinical examination was significant for testicular volume 4-5 ml bilaterally, penile length of 7.5 cm, and absence of axillary or pubic hair. Laboratory tests revealed increased gonadotropins and testosterone levels (FSH: 2.2 mIIU/ml, LH: 1.65 mIU/ml, testo: 1.65 ng /ml). The levels of CEA, βhCG, aFP, 17-OH-PG, DHEAS, TSH, fT4, and cortisol were normal. Clinical and laboratory findings established the diagnosis of central precocious puberty (CPP). The combination of "gelastic seizures" with CPP in a 4-year-old boy raised the suspicion of a hypothalamic hamartoma. The MRI of the sella turcica region revealed a lobular mass of 2.82*2.42*2.4 cm with slight heterogeneity, signal intensity similar to grey matter, with no contrast enhancement located in the hypothalamic-suprasellar-mamillary bodies region of the brain, extending to the wall of the 3rd ventricle and in contact with the anterior lobe of the pituitary gland. The differential diagnosis of the radiographic image included hypothalamic hamartomas, gliomas, and craniopharyngiomas. To further investigate the CNS mass, an in vivo MRS of the brain was performed. The metabolites that were detected were N-acetyl aspartate (NAA), creatine (Cr), choline (Cho), and myoinositol (MI), as well as lipids and macromolecules. Compared to the spectrum of healthy controls, the NAA/Cr quotient was lower (30% of normal), the Cho/Cr quotient was normal and the MI/Cr quotient was slightly elevated. These findings, in combination with the findings of conventional MRI, were consistent with the diagnosis of a hypothalamic hamartoma.

Conclusion: Hypothalamic hamartoma is the most common type of CNS tumour that causes CPP, especially in very young children, and is often associated with gelastic seizures. MRS is a state-of-the-art, non-invasive, imaging technique that compares the chemical composition of normal tissue to that of abnormal regions, by juxtaposing the frequency of measured metabolites. MRS, in combination with clinical evaluation and classic MRI, can provide identification of CNS masses, thus eliminating the need for an invasive biopsy.