下垂体腫瘍との鑑別が困難であったトルコ鞍部Germinomaの1例

A Case of Sellar Germinoma which was Misdiagnosed as Pituitary Adenoma

I．はじめに

　傍鞍部germinomaは小児期に発生し^6,9,10），尿崩症をほぼ必発とし^9,10），鞍上部腫瘍としてのCT所見などによって比較的容易に術前診断を得やすい腫瘍である．ところがわれわれは，無月経を主訴とし，臨床的に尿崩症を呈することなく，画像診断でも下垂体腺腫との鑑別が困難であったトルコ鞍部germinomaの成人女性例を経験したので報告する．

Abstract

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 re-vealed 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 72ng/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 intrasel-lar tumor which had a suprasellar portion (vertical length : 15mm) . T1 weighted MRI revealed low in-tensity tumor, and T2 weighted image revealed high in-tensity tumor. Sagittal MR image with gadolinium en-hancement 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 consi-dered 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.