1/20. somatostatin receptor scintigraphy of a patient with a giant invasive prolactinoma.A 41-year-old with a giant prolactinoma underwent in-111 pentetreotide (octreotide) imaging showing very intense tracer uptake in the region of the anterior skull base. In contrast, there was no significant response to octreotide therapy. Prediction of clinical responsiveness to octreotide therapy in patients with pituitary adenomas may depend on the presence of somatostatin receptor subtype 5. Pentetreotide does not avidly bind to this receptor subtype and therefore, cannot be used clinically to predict therapeutic octreotide responsiveness in patients with large prolactinomas.- - - - - - - - - - ranking = 1keywords = giant (Clic here for more details about this article) |
2/20. Giant insulinoma in a patient with multiple endocrine neoplasia-type I: a case report.We report a case of giant cystic insulinoma constituting part of multiple endocrine neoplasia (men) type I. A 29-year-old Japanese man presented with a history of recurrent hypoglycemic attacks. Endocrine examination showed hyperinsulinemia discordant with hypoglycemia, and a giant cystic insulinoma (11 x 10 cm) located in the pancreatic tail was detected radiologically. hyperprolactinemia due to pituitary adenoma and hyperparathyroidism due to parathyroid hyperplasia were also present. The insulinoma, prolactinoma and hyperplastic parathyroid gland were surgically removed. Fluorescent microsatellite analysis detected loss of heterozygosity (LOH) in chromosome 11q13 in dna samples from all resected tissues but not from white blood cells. This is a rare case of men type I because of the giant cystic insulinoma and the evidence of common LOH detected in all men type I tissues.- - - - - - - - - - ranking = 0.6keywords = giant (Clic here for more details about this article) |
3/20. Giant prolactinoma presented as unilateral exophthalmos in a prepubertal boy: response to cabergoline.We report the case of a giant prolactinoma in a 7-year-old boy, which was complicated by unilateral exophthalmos. The initial levels of prolactin (PRL) were about 80,000 microU/ml. Treatment with cabergoline (CAB) resulted in rapid normalization of serum PRL (6 weeks after initiation of treatment) and reduction of tumor size. In particular, magnetic resonance imaging (MRI), which was done 2.5 months after the patient was put on CAB, revealed tremendous improvement with a decrease in the size of the tumor which now showed no extrasellar extension. Subsequent MRI studies demonstrated further improvement. exophthalmos, anisocoria and visual fields improved. In summary, this patient represents the first report of the therapeutic use of CAB as the primary mode of treatment in a 7-year-old boy with infiltrative giant prolactinoma complicated by unilateral exophthalmos. It is a noninvasive treatment that can preserve and restore vision, as well as pituitary function, and is preferable to surgery or radiation in the treatment of prolactin-secreting macroadenoma in childhood and adolescence.- - - - - - - - - - ranking = 0.4keywords = giant (Clic here for more details about this article) |
4/20. A giant prolactinoma presenting with unilateral exophthalmos: effect of cabergoline and review of the literature.We report the case of a 45-year-old male presenting with unilateral exophthalmos due to a large tumoral mass invading the skull base. Ophthalmologic examination did not show any visual field defects. Imaging techniques demonstrated extension of a huge tumor (approx. 8x8x8 cm) into the right orbit and nasopharynx. Endocrine work-up revealed grossly elevated serum prolactin (PRL) levels (26,466 microg/l, nl. < 12), pointing to a large, invasive macroprolactinoma. Stimulation tests indicated associated partial adrenal and growth hormone deficiencies. Planned surgery was abandoned, and the patient was instead treated with the long-acting dopamine agonist, cabergoline. Over a period of one year, serum PRL dropped to 131 microg/l, while the tumor mass shrank to less than 50% of its original volume (with 3.5 mg/week of cabergoline). The exophthalmos disappeared, and the patient did not develop rhinorrhea or any other side effects from treatment with cabergoline. The efficacy was maintained throughout the second year (ultimate serum PRL 74 microg/l, and final size less than 10% of the original). With reference to this case, we review other macroprolactinomas reported in the recent literature for associated exophthalmos, grossly elevated serum PRL levels (> or = 15,000 microg/l), and/or "giant" size (> or = 4 cm in maximum diameter). We highlight the use of dopamine agonists in the treatment of prolactinomas with such unusual characteristics.- - - - - - - - - - ranking = 1keywords = giant (Clic here for more details about this article) |
5/20. Rapid re-expansion of a macroprolactinoma after early discontinuation of bromocriptine.Prolactin (PRL)-secreting pituitary adenomas are the most common functioning pituitary tumors. Medical treatment with dopamine agonists is the therapy of choice for macroprolactinomas (> or = 10 mm). Withdrawal of bromocriptine after weeks or months of uninterrupted therapy has been associated with rapid tumor re-expansion as evidenced by x-ray and CT scanning of the pituitary region. We report a patient with a giant macroprolactinoma who had a dramatic response to bromocriptine (tumor volume shrinkage of 53% within a month) but rapid re-expansion to its original dimensions one week after discontinuation of bromocriptine. To our knowledge, this is the first time that the rapid shrinkage/re-expansion of a macroprolactinoma has been documented with serial MRI scans.- - - - - - - - - - ranking = 0.2keywords = giant (Clic here for more details about this article) |
6/20. Giant prolactinomas presenting as skull base tumors.BACKGROUND: Prolactinomas invading the skull base are rare, and could easily be confused with skull base tumors of nonpituitary origin. CASE DESCRIPTION: We report a series of 4 cases of giant prolactinomas invading the skull base and presenting with atypical symptoms. Case 1 presented with a short history of headache and nasal obstruction. Case 2 presented with progressive hypoacusia, dizziness, and ophthalmoplegia. In Case 3, the patient developed rapid progressive visual failure and psychiatric symptoms. Case 4 presented with a 1-year history of headache and retrorbital pain. The diagnosis of prolactinoma was made on the basis of tumor immunohistochemistry and/or high plasma prolactin levels (range from 650-6,500 ng/mL). Medical treatment with the dopamine agonist cabergoline was given; it was effective in normalizing prolactin levels and inducing tumor shrinkage. CONCLUSION: Prolactin levels should be measured in all large skull base tumors involving the pituitary region before any surgery or inappropriate radiotherapy is performed.- - - - - - - - - - ranking = 0.2keywords = giant (Clic here for more details about this article) |
7/20. A case of macroprolactinoma with subclinical growth hormone production.We describe a rare case of macroprolactinoma with subclinically synchronous growth hormone (GH) production. A 59-year-old man with a giant adenoma in his pituitary had elevated serum prolactin (PRL) and insulin-like growth factor (IGF)-I levels, despite normal levels of basal GH. serum GH levels were paradoxically increased in response to an intravenous administration of thyrotropin-releasing hormone (TRH). Prolonged exposure to glucose as a result of oral glucose tolerance testing (oGTT) failed to decrease GH levels. Two-week treatment with cabergoline, a dopamine D2 receptor agonist, decreased serum PRL and GH levels, and size of the tumor. immunohistochemistry and in situ hybridization revealed PRL-producing cells capable of synchronous GH production. Acidophilic stem cell adenoma may be responsible for these phenomena. The nature of high proliferation and invasive tumor growth should be kept in mind when managing patients with this cell type of adenoma. IGF-I levels should be followed in PRLoma, even when basal GH levels are within the normal range, because mixed PRL- and GH-producing tumors would lie underneath. Further endocrinological examinations such as TRH test and oGTT are recommended when elevated IGF-I levels are detected.- - - - - - - - - - ranking = 0.2keywords = giant (Clic here for more details about this article) |
8/20. "Hook effect" in prolactinomas: case report and review of literature.OBJECTIVE: To present a case of the "hook effect" occurring in the prolactin immunoassay in a patient with giant prolactinoma and to review this phenomenon. methods: We describe the clinical, biochemical, radiologic, and pathologic data of a patient with a giant prolactinoma, in which dilution testing of serum prolactin levels confirmed the presence of the hook effect. We discuss the historical and mechanistic aspects of the hook effect and then review its occurrence with the prolactin assay. RESULTS: A 65-year-old man sought medical attention because of headaches, personality changes, and "bulging" eyes. Cranial magnetic resonance imaging disclosed a 10-cm-diameter, lobulated, heterogeneous, locally invasive mass in the anterior skull base and cranial fossa. Initial laboratory testing showed a prolactin level of 164.5 ng/mL (normal range, 1.6 to 18.8). The pathology specimen from his surgical debulking procedure was consistent with prolactinoma. Retesting of the original serum prolactin sample with serial dilutions revealed a prolactin level of 26,000 ng/mL. A postoperative diluted prolactin level was 22,000 ng/mL. Both prolactin samples demonstrated the hook effect. Dopamine agonist therapy was initiated, and the prolactin level and size of the tumor decreased substantially. The hook effect most commonly occurs when excess antigen (for example, prolactin) is present during testing. Dilution testing can counteract this assay phenomenon. CONCLUSION: Clinicians should be aware of this laboratory phenomenon when evaluating large pituitary or parasellar masses. When the hook effect is suspected, dilution testing of prolactin samples may prevent incorrect diagnosis and unnecessary surgical intervention in patients with prolactinomas.- - - - - - - - - - ranking = 0.4keywords = giant (Clic here for more details about this article) |
9/20. The novel use of very high doses of cabergoline and a combination of testosterone and an aromatase inhibitor in the treatment of a giant prolactinoma.Most prolactinomas respond rapidly to low doses of dopamine agonists. Occasionally, stepwise increases in doses of these agents are needed to achieve gradual prolactin (PRL) reductions. Approximately 50% of treated men remain hypogonadal, yet testosterone replacement may stimulate hyperprolactinemia. A 34-yr-old male with a pituitary macroadenoma was found to have a PRL level of 10,362 micro g/liter and testosterone level of 3.5 nmol/liter. Eleven months of dopamine agonist therapy at standard doses lowered PRL levels to 299 micro g/liter. Subsequent stepwise increases in cabergoline (3 mg daily) further lowered PRL levels to 71 micro g/liter, but hypogonadism persisted. Initiation of testosterone replacement resulted in a rise and discontinuation in a fall of PRL levels. Aromatization of exogenous testosterone to estradiol and subsequent estrogen-stimulated PRL release was suspected. Concomitant use of cabergoline with the aromatase inhibitor anastrozole after resuming testosterone replacement resulted in the maintenance of testosterone levels and restoration of normal sexual function, without increasing PRL. Ultimately, further reduction in PRL on this therapy permitted endogenous testosterone production. Thus, novel pharmacological maneuvers may permit successful medical treatment of some patients with invasive macroprolactinomas.- - - - - - - - - - ranking = 0.8keywords = giant (Clic here for more details about this article) |
10/20. The hook effect in prolactin immunoassays.We describe a young female patient with giant invasive sellar and suprasellar tumor and modest elevation of prolactin to 165 ng/ml (normal range 3-29). A diagnosis was made of non functional pituitary adenoma with stalk effect, causing moderate prolactin elevation. A surgery for the removal of the tumor was advised but the patient declined. Treatment with a dopamine agonist was not offered. The patient presented 2 years later with deterioration of her vision and serum prolactin of >16000 ng/ml. Debulking transsphenoidal surgery was performed. The staining of tissue confirmed prolactinoma. Medical treatment with bromocriptine was initiated. We believe that the discrepancy between the 2 values of serum prolactin, is most probably caused by a hook effect in the initial prolactin assay. The mechanism of the hook effect and its occurrence with prolactin immunoassays and methods to eliminate this effect is discussed. Hook effect needs to be suspected in every patient with a giant pituitary or parasellar mass and serum prolactin <200 ng/ml. Assaying a diluted serum will usually unmask this phenomenon and allow accurate diagnosis and management.- - - - - - - - - - ranking = 0.4keywords = giant (Clic here for more details about this article) |
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