zaki
Forum Guru
Topics: 92
Posts: 398
|
A 38-year-old woman is referred to you by her gynecologist. She first presented to her gynecologist 4.5 years ago with amenorrhea of 3 years’ duration and galactorrhea of 1 year’s duration. She had been taking no medications, and her initial physical examination was unremarkable except for expressible galactorrhea bilaterally. A routine chemistry screen was normal; her T4 level was 7.8 µg/dL, serum TSH was 1.4 µU/mL, and prolactin level was 48.2 ng/mL.
After taking bromocriptine for 2 months, her prolactin level was 19 ng/mL, at which point her galactorrhea ceased and she had her first menstrual period in 3 years. She continued to take bromocriptine over the next 4 years; her prolactin level remained less than 20 ng/mL, and she continued to have regular periods. However, she stopped taking her bromocriptine 6 months ago and is now having progressively worse headaches.
Her prolactin level is now 60.5 ng/mL, and a visual field examination shows a small superotemporal field cut in the right eye. A computed tomographic (CT) scan shows a 2.4-cm ´ 1.6-cm sellar mass with considerable suprasellar extension. She is now referred to you for further management.
What is the most likely diagnosis?
(A) Prolactinoma
(B) Clinically nonfunctioning pituitary adenoma
(C) Metastatic cancer to the sella
(D) Craniopharyngioma
___________________
Maverick
|
| Idiopathic
Forum Guru
Topics: 19
Posts: 641
|
This looks like prolactinoma to me.
|
| Ouli Maty
Forum Elite
Topics: 33
Posts: 275
|
But the prolactin level should be more than 150 in Prolactinoma, whereas Clinically nonfunctioning pituitary adenoma can cause a mild elevation of prolactin secondary to compression of the stalk.
___________________
deep breathing...
|
| zaki
Forum Guru
Topics: 92
Posts: 398
|
Answer: B
Educational Objective: Understand the concept of hyperprolactinemia due to hypothalamic stalk dysfunction and differentiate prolactinoma from a nonsecreting pituitary adenoma in a patient with hyperprolactinemia.
Prolactin (PRL) is regulated by both PRL-releasing hormones (thyrotropin-releasing hormone, vasoactive intestinal polypeptide) and inhibiting hormones (primarily dopamine). Unlike the other pituitary hormones, the dominant effect of the hypothalamus is inhibitory; if there is disruption of portal blood flow or a lesion of the mediobasal hypothalamus, PRL levels rise, whereas other pituitary hormone levels fall. The rise due to hypothalamic stalk dysfunction is usually mild to moderate; levels rarely rise above 150 ng/mL. Minimal degrees of hypothalamic stalk dysfunction may cause hyperprolactinemia while at the same time allowing normal adrenocorticotropic hormone (ACTH) and thyroid-stimulating hormone (TSH) function to be present.
Intrasellar lesions rarely cause hyperprolactinemia, and it usually requires a large lesion with suprasellar extension to cause sufficient stalk compression to induce hyperprolactinemia. A similarly sized prolactinoma would usually cause PRL levels to be in the 500 to 20,000 ng/mL range. Thus, this patient with a large lesion would have a PRL level that would not be compatible with a prolactinoma. Therefore, it is important to consider other lesions that could be present and that would cause hyperprolactinemia by the mechanisms outlined above.
The most common lesion is a nonsecreting pituitary adenoma, which is what this patient has. This is far more common than a craniopharyngioma. The chronicity of the course, despite the recent worsening headaches, makes metastatic cancer to the sella unlikely.
Large tumors with only modestly elevated PRL levels are likely not prolactinomas and must be evaluated further for other causes. In this case, the bromocriptine was able to decrease the PRL levels and may even have caused a decrease in tumor size, which occurs in about 10% of such patients. The development of increased headaches after the patient stopped taking bromocriptine is compatible with such a possibility.
The key mistake made in this case was not obtaining a computed tomographic (CT) or magnetic resonance imaging (MRI) scan as part of the initial evaluation. Once hypothyroidism, medication use, pregnancy, renal insufficiency, and cirrhosis were excluded by the initial examination and laboratory tests, a CT or MRI scan is mandatory to exclude a mass lesion in the area.
___________________
Maverick
|
| Ouli Maty
Forum Elite
Topics: 33
Posts: 275
|
Are you a Prof or what?
This is wonderful.
Thanks Zaki.
___________________
deep breathing...
|
| Medicine Guy
Forum Junior
Topics: 11
Posts: 68
|
Thank you zaki  WOW man
___________________
www.xpindia.com - affordable medical web hosting
|
|
| |
| | | | | | |
