Diagnosis of Cushing's Disease by Inferior Petrosal Sinus Sampling (IPSS): Evidence of False Negative Results / 대한내분비학회지

BACKGROUND: While inferior petrosal sinus sampling (IPSS) correctly diagnoses pituitary dependent Cushings syndrome if a significant ratio of plasma ACTH between the IPS and the peripheral blood is demonstrated, little has been said about the significance of a negative ratio in Cushings disease (e.g. false negative result). We evaluated the results of IPSS with Cushings disease, and compared them with imaging findings through transsphenoidal surgery. METHODS: 29 patients with Cushings disease underwent transsphenoidal examination of the pituitary gland from 1989 to 1998 at Seoul National University Hospital were evaluated. We compared the results of IPSS and imaging findings with sellar CT or dynamic MRI. The ratio of the ACTH concentrations at the IPS and in the peripheral blood (IPS:P ratio) and the ratio of the ACTH concentrations between the IPSs (interpetrosal ratio) were calculated before and after CRH infusion. RESULTS: With IPSS the diagnosis of Cushings disease was possible in 90% (26/29), and 3 cases in whom IPSS did not show significant IPS:P ACTH ratio were confirmed to be Cushings disease through hemihypophysectomy of lesion suspected by sellar dynamic MRI and achieved remission after operation (e.g. false negative result of diagnosis for Cushings disease by IPSS). However, accurate localization of microadenoma was achieved in only 59% (17/29). Imaging study detected microadenoma in 76% (22/29) and correctly localized in 66% (19/29). Both IPSS and imaging study precisely localized the pituitary microadenoma in 10 (34.5%) cases of 29 cases and a discrepancy between two studies existed in 7 (24.1%) cases in which the imaging study correctly localized microadenoma in 6 cases and IPSS in 1 case. CONCLUSION: Only when a significant IPS:P ACTH ratio is present can Cushings disease be established by IPSS. The absence of a significant IPS:P ACTH ratio does not necessarily imply ectopic secretion of ACfH, nor does it exclude Cushings disease. The results of lateralization by IPSS do not remove the need for transsphenoidal examination of the sella turcica because false negative result can be. IPSS and radiologic study should be complementary used in diagnosis of Cushings disease and localization of microadenoma, as IPSS can be used when sellar imaging study failed to visualize the lesion and hemihypophysectomy of suspected lesion by imaging study can be considered when IPSS did not show significant ratio of ACTH.

A Case of Cushing's Disease due to Large Pituitary Adenoma Treated by Surgery in Combination with Radiotherapy / 대한내분비학회지

Large pituitary adenomas causing Cushings disease are uncommon, and usually present with mild manifestations of Cushings syndrome. Large adenomas may have rapid growth and quickly reach a size large enough to become clinically apparent. These tumors are more frequently invasive than microadenomas, their widespread extensions make radical surgical removal difficult and the ultimate clinical course malignant. We report a case of 37 year-old women presenting amenorrhea, weight gain, and moon face. Sellar magnetic resonance imaging(MRI) demonstrated a large lobulating tumor measuring 3.5cm in diameter, arising from sella turcica, extending up to suprasellar area and invading the cavernous sinuses. Transfrontal adenectomy was performed to remove a mass, but residual mass was remained after surgery. Subsequent external brain radiotherapy(total dose 5400cGy) was performed. Histology revealed an adrenocorticotrophin(ACTH) secreting pituitary adenoma. After treatment, her menstration was started, body weight was reduced, and moon face was disappeared.

The Localization of Microadenoma with Sella Imaging Study and Inferior Petrosal Sinus Sampling in Cushing's Disease / 대한내분비학회지

Background: Inferior petrosal sinus sampling(IPSS) is known to be useful for the differential diagnosis of ACTH-dependent Cushings syndrome and for the preoperative lateralization of pituitary microadenoma. We tried to analyze the relative value of IPSS in localization of microadenoma as compared with sella imaging study including computerized tomogram(CT) or magnet resonance imaging(MRI) in Cushings disease. Methods: We reviewed the clinical records of 21 patients with Cushings disease who underwent IPSS and the radiologic study such as sella CT or sella MRI preoperatively followed by transsphenoidal microsurgery. By pathologic examination including immunohistochemistry and postoperative clinical and biochemical evaluation we confirmed the diagnosis of Cushings disease due to pituitary microadenoma in all 21 cases. Results: Sella CT or sella MRI detected microadenoma in 57.1% of cases( =12/21), while recently available dynamic MRI did so in 7 out of S cases. With IPSS the diagnosis of Cushings disease was possible in 90.5% of cases(= 19/21), but accurate lateralization of microadenoma was achieved in only 63.2% of cases( =12/19). IPSS precisely localized the pituitary microadenoma in 6 out of 9 cases whose lesion were not detected by the radiologic study. Of 7 cases in which IPSS failed to localize microadenoma, the radiologic study detected the lesion in 6 cases. Of 5 cases in which IPSS and the radiologic study showed a discrepancy in location of microadenoma, the radiologic study correctly localizaed the lesion in 4 cases and IPSS did so in one case. Conclusion: IPSS is not more reliable than sella imaging study for preoperative localization of microadenoma in Cushings disease. However it might have a complementary role, especially when sella imaging study failed to visualize the lesion.