An intrasellar germinoma with normal cerebrospinal fluid beta-HCG concentrations misdiagnosed as hypophysitis.

A patient with an intrasellar germinoma leading to pituitary stalk thickening is reported. The patient, a 24-year old woman, presented with hyperprolactinemia, secondary hypothyroidism, and hypogonadotropic hypogonadism with no evidence of diabetes insipidus. Cerebrospinal fluid (CSF) examination revealed an increased number of lymphocytes and histiocytes. Although beta-HCG concentration was normal (<2 mIU/mL) in the CSF, increased beta-HCG concentration was detected in the serum. Systemic glucocorticoid treatment led to a decrease in CSF cell count, but no regression of the sellar mass was noted. A diagnostic biopsy was performed and showed an intrasellar germinoma. The patient underwent conventional radiotherapy. Complete resolution of the mass lesion and normalization of beta-HCG concentration in the serum were observed three months after radiotherapy. The presence of intrasellar mass lesion in association with pituitary stalk thickening may cause difficulties in the differential diagnosis. Histopathological examination is essential in equivocal cases in order to reach accurate diagnosis and apply the most appropriate therapy.