[A case of sellar germinoma which was misdiagnosed as pituitary adenoma]

The authors reported a rare case of sellar germinoma which was misdiagnosed as nonfunctioning pituitary adenoma. A 32-year-old woman was admitted to our hospital because of amenorrhea and disturbance of left visual acuity. She had become amenorrhagic after her second delivery two years before. Neurological examination revealed she was normal except for diminished left visual acuity (Rt. = 1.2, Lt. = 0.5). The general condition was good. Urine volume and its specific gravity were within normal range. Endocrinological examination showed hyperprolactinemia (PRL 72 ng/ml) accompanied with impairment of GH, TSH, LH and FSH's reserve. Basal levels and reserve of the blood cortisol were normal. AFP and hCG were within normal range. CT scan revealed a homogenously enhanced intrasellar tumor which had a suprasellar portion (vertical length: 15 mm). T1 weighted MRI revealed low intensity tumor, and T2 weighted image revealed high intensity tumor. Sagittal MR image with gadolinium enhancement showed the pituitary gland anterior to the tumor. Transsphenoidal removal was performed. The histological diagnosis was pure germinoma. After the operation, the intracranial and spinal disseminations were disclosed. Complete neuraxis irradiation resulted in the complete remission of the tumor. Sellar germinoma without diabetes insipidus is considered to be very difficult to diagnose preoperatively. However, the authors proposed that anterior shift of the pituitary gland in sagittal MR image may be a clue to the diagnosis of sellar germinoma.