Abstract
INTRODUCTION
Germinomas are rare malignant intracranial neoplasms which most commonly occur in young males in the pineal and suprasellar region. Less commonly, germinomas arise in the sellar region, where there is slight female predominance. Diagnostic challenges may arise, as autoimmune hypophysitis has similar clinical, imaging and histopathological features to germinoma. CASE REPORT: A 16-year-old girl (46, XX) presented with primary amenorrhea, failure of sexual development and growth delay. Stimulation tests confirmed panhypopituitarism except diabetes insipidus. Infectious and rheumatological workup was negative. She had normal levels of beta HCG, CEA and alpha-fetoprotein. MRI brain identified an enhancing hypothalamic pituitary stalk and pituitary mass. A biopsy was performed which showed a lymphocyte rich infiltration of the pituitary gland, suggesting autoimmune hypophysitis. She completed 4 cycles of low dose methotrexate weekly and remained on hormone replacement therapy for panhypopituitarism for three years until she developed daily headaches, blurry vision, and secondary amenorrhea. MR imaging showed increased nodularity at the pituitary infundibulum with involvement of the optic chiasm. This lesion progressed on mycophenolic acid, increased doses of hydrocortisone, high doses of prednisone and IV methylprednisolone. She was unable to tolerate azathioprine and rituximab after one year. Subsequently, she underwent partial resection of the suprasellar lesion with the pathology showing germinoma admixed with abundant lymphohistiocytic inflammation. A nongerminomatous component was not present histologically and CSF only showed an elevated beta HCG. Given that the tumor is localized to the central nervous system she is receiving treatment via SIOP CNS GCT 96 protocol.
DISCUSSION
Autoimmune hypophysitis and germinoma can share similar clinical, radiological and histopathological features. Our case demonstrates the need for careful histologic examination, close clinical and radiological follow up in patients with lymphocyte-rich suprasellar lesions if no response to immunosuppressant therapy is noted.
RARE-11. SELLAR GERMINOMA MASQUERADING FOR SIX YEARS AS AUTOIMMUNE HYPOPHYSITIS IN A 16-YEAR-OLD GIRL WITHOUT DIABETES INSIPIDUS
