Human chorionic gonadotropin elevation is not an intracranial germ cell tumor signature

Abstract

Dear editor, For many years, in case of suspicion of a germ cell tumor (GCT), human chorionic gonadotropin (HCG), its beta subunit and alpha-fetoprotein (AFP) have been used as specific markers in the blood and/or cerebrospinal fluid (CSF) for clinical decision-making [4]. A positive test is an indication for treatment, without requiring histological confirmation [5]. We report a first description of CSF HCG elevation in a non-cystic suprasellar craniopharyngioma, contradicting this dogma. A 52-year-old male with a history of arterial hypertension and tinnitus complained of a decrease in left-side visual acuity over a few weeks, associated with polyuro-polydipsia syndrome. MRI examination revealed a suprasellar lesion of 16×18×16 mm, with a moderate hyper-T2 signal and an iso-T1 signal with homogeneous gadolinium enhancement. The lesion did not have a cystic component (see Fig. 1). Spinal MRI was negative, and the cerebral CT scan did not show any calcification of the tumor. Hormone analysis revealed a pituitary deficiency. Biological analysis of the CSF performed as part of the etiological assessment revealed an elevation of HCG to 10.8 IU/l (normal levels <5 IU/l) and of free beta-HCG to 1.1 ng/ml (normal levels <0.1 IU/l). Elevation of AFP was not detected in the blood or CSF. No abnormal cells were found in the CSF. No elevation of these markers was found in the blood. Given the many atypical features in our patient, we decided to perform a robot-assisted stereotaxic biopsy. The final diagnosis was papillary craniopharyngioma and excluded germinoma. Due to the high risk of surgical treatment, and after a multidisciplinary discussion, the tumor was treated by radiotherapy. Six months after that, the patient recovered his visual field loss, but the hypopituitarism remained. The MRI showed a volumetric reduction of the tumor and a decrease in contrast enhancement. This report points out two issues: First, some authors [2, 3, 6] have suggested that many cystic pineal, sellar or suprasellar lesions, including cystic craniopharyngioma, are able to produce theses markers through their wall (descriptions of HCG in benign pineal cyst contents and walls). This observation of a solid craniopharyngioma demonstrates for the first time that the tumor itself is able to secrete low levels of HCG and β-HCG that may be detectable in the CSF. CSF AFP elevation was also detected in two cases of craniopharyngiomas, one of which was proven to be a malignant form [2]. So far, no blood elevation of these markers has been reported in craniopharyngiomas. Second, therefore, physicians involved in brain management need to be aware that HCG or AFP CSF positivity in a patient with a suprasellar tumor is not a specific GCT signature and is not enough information for making therapeutic decisions. Our clinical case underlines the importance of multidisciplinary discussions and the necessity to perform a biopsy in patients showing isolated suprasellar lesions (bipolar pineal and suprasellar locations remain suggestive of germinoma), positive for CSF markers but with atypical P. Bourdillon (*) : E. Jouanneau Department of neurosurgery A, Hopital Neurologique et Neurochirurgical Pierre Wertheimer, Hospices Civils de Lyon, 59 bd Pinel, 69500 Bron, France e-mail: pierre.bourdillon@neurochirurgie.fr