異常高プロラクチン血症とCB−154テストで2相性反応を呈した男性プロラクチン産生下垂体腺腫の1例

A CASE OF MALE PROLACTINOMA PRESENTING EXTREMELY HIGH SERUM PROLACTIN LEVELS AND BIPHASIC RESPONSE TO CB-154 SUPPRESSION TEST

　抄録　異常高プロラクチン血正症を呈し，CB−154テストで2相性反応が認められたプロラクチン産生下垂体腺腫の症例を報告した。33歳，男性，神経学的には異常所見はなかったが，頭蓋単純写でトルコ鞍の広範な破壊，CTおよび脳血管写所見でトルコ鞍から左中頭蓋窩に広範に伸展した腫瘍性病変を認めた。下垂体機能検査におけるプロラクチン（PRL）の基礎値は70,00 ng／mlと異常高値を呈し，かつ，CB−154テストでPRL値は通常初期から抑制をうけるが，本例では90分値まで前値の2.5倍（178,400ng／ml）と上昇し，その後120分値よりようやく抑制された値を示し始めた。TRHテストでは遅延および遷延型の反応がみられた。手術による組織診断はPRL産生重下重垂体腺腫であった。高PRL血症の原因として，本症では単に腫瘍が大きいことおよび海綿静脈洞への浸潤のほかに，培養および組織所見から個々の腫瘍．細胞のPRL産生分泌能亢進が重要であると考えられたので報告した。またTRHテストおよび組織培養の結果は，本腫瘍が視床下部からの影響も受けている可能性を示唆するものであり，この点も本症例に特異な点と考え報告した。

A 33-year-old male was admitted to the Depart-ment of Neurosurgery, Fukui Medical School with a complaint of headache. There were no neurolo-gical deficits on admission. Craniogram demonst-rated a so-called "phantom sella". A computed tomography revealed a high density mass lesion and the mass was enhanced well, that mainly extended from the sella to the left middle cranial fossa. The left carotid angiogram revealed an avascular mass lesion extending from the sella to the left middle cranial fossa. Pituitary function tests revealed an extremely high serum prolactin (PRL) levels (70,100ng/ml). PRI. response to TRH was delayed in peak and the high level continued. Serum PRI, levels elevated to 90,800ng/ml at 180 min after injection of TRH. A biphasic re-sponse was demonstrated in response to CB-154 suppression test to PRI, secretion, that is, CB-154 stimulated PRL release initially (up to 90 min) and suppressed thereafter. Serum PRI. levels (178,400ng/ml) reached to peak about 90 min after CB-154 administration. Response of growth hor-mone (GH) and adrenocorticotropic hormone(ACTH) to insuline were also impaired. Cranio-tomy was performed. The tumor was partially removed and was diagnosed as a prolactinoma histologically. Tumor tissue removed was subjec-ted to the monolayer culture and electron micro-scopic study. Their observations demonstrated hyperactive PRI. secretion of the individual cells. A total dose of 5,000 rads was irradiated post-operatively. After irradiation, serum prolactin levels dropped to 2,600ng/ml and the size of tumor was reduced. Bromocriptine was administ-rated after irradiation.

The possible causes of the hyperprolactinemia and the biphasic response to CB-154 suppression test in this case are discussed.