Clinical and Endocrinologic Differences between Prolactinoma and Pseudoprolactinoma Proven by Immunohistochemical Study / 대한내분비학회지

ABSTRACT

Hyperprolactinemia is the most common hypothalamo-pituitary disorder encountered in clinical endocrinology. Excluding the drug-induced hyperprolactinemia, the most common cause of this disorder is a pituitary tumor. Prolactinoma is mainly made up of prolactin-secreting cells but pseudoprolactinoma is tumor that does not secrete prolactin itself. The pseudoprolactinoma interrupts the flow of prolactin inhibiting factor, dopamine, from the hypothalamus through the pituitary stalk to the normal pituitary. The differentiation prolactinoma from pseudoprolactinoma is vitally important since true prolactinomas are most commonly responded well in terms of tumor shrinkage to medical treatment using dopamine agonist therapy, whereas pseudoprolactinomas do not. Thus surgical treatment is clearly indicated as first-line treatment if we know that a lesion is a pseudoprolactinoma. We compared prolactinoma with pseudoprolactinoma in clinical and endocrinologic characteristics of 48 cases after immunohistochemical diagnosis. We could not find any differential point of both tumors in clinical and radiological characteristics although some differences were exist. But we had found the relationship between the mean level of pretreatment serum prolactin and the presence of positive immunohistochemical stain for prolactin. The pretreatment serum prolactin level was significantly higher in patients with tumors showing many prolactin immunohistochemical staining cells than in those with none(p<0.05). When the pretreatment serum prolactin exceeded 100ng/ml, the tumors contain 94% of prolactin positive cells in stain. So, if the pretreatment serum prolactin exceeds 100ng/ml, we primarily suspect prolactinoma and medical treatment should be considered. If the pretreatment level below 100ng/ml, we suspect pseudoprolactinoma and surgical treatment should be considered.