Dissociation Between IPSS Lateralization of Pituitary Microadenoma and MRI Image in a Patient with Cushing's Disease: Post-Surgical Outcome

Presentation Number: SUN-0789
Date of Presentation: June 22nd, 2014

Ester Matilde Pardes*1, Lucas Lisandro Gutnisky2, Fabiana Fierro3, Fernando Latorre3, Antonio Colobraro3, Patricia San Martín2 and Amelia Rogozinski3
1Hospital Ramos Mejía, Buenos Aires, Argentina, 2J M Ramos Mejía Hospital, Buenos Aires, Argentina, 3J. M. Ramos Mejía Hospital, Buenos Aires, Argentina

Abstract

BACKGROUND: ACTH-dependent Cushing´s Syndrome (CS) can present difficulties in identifying the ACTH source. Cushing´s disease (CD) once diagnosed can also present difficulties in identifying pituitary microadenoma lateralization due to discordant studies. We present a patient with CD and dissociated results between MRI image and inferior petrosal sinus sampling (IPSS) lateralization.

CLINICAL CASE: A 27-year-old man with classical stigmata of CS (moon facies, supraclavicular fat pads, acne, abdominal red-purple striae),  ankle edema, and hypertension treated with enalapril consulted us.  BMI- 28,3 kg/m2, BP- 130/100 mmHg.  ACTH-dependent CS was confirmed:  plasma ACTH-183 pg/ml (n< 48 pg/ml), 24hr-urinary free cortisol (UFC)-2145 ug/24 hs (n<90 ug/24 hs), cortisolemia post-1mg dexamethasone (DXM)-38,9 ug/dl. Basal cortisolemia-30,1 ug/dl and post 8mg- DXM-37ug/dl.

MRI showed a left pituitary microadenoma (5,7 mm); 3T-MRI suggested a left pituitary microadenoma but it also showed a discrete right hypodense area.

IPSS was requested to distinguish CD from an ectopic ACTH-syndrome. Co-secretion products were also determined :catecholamines, VMA, cromogranin, calcitonin- with normal results. Neck and chest CT scans were normal. Abdominal CT scan showed hyperplasic adrenal glands.

IPSS (basal ACTH at -10' and 0' and  post- DDAVP  at  2,'  5 'and 10') confirmed pituitary ACTH secretion with right lateralization:

 ACTH (pg/ml)                                             -10´             0'              2´          5´         10´

Peripheral Sample                                      130            127,2       147,8       175,4     228,8     

Right IPSS                                                 686,3        >1000       6279        4348      2934

Left IPSS                                                    195            239,9      792,9       543,3     582,1

Endoscopic pituitary surgery was indicated and a left microadenoma was resected. Before surgery he received ketoconazol,decreasing UFC to 250 ug/24h.

Plasma ACTH was measured  before surgery: 137 pg/ml and 24 hr-after surgery < 5 pg/ml. Hydrocortisone (HC)  treatment was indicated. At 14 days post surgery (withdrawing HC for 24 hs)- 8:00 a.m- plasma cortisol was <1 ug/dl and ACTH- 13 pg/ml.

Histological examination confirmed pituitary adenoma with ACTH+ immunostaining.

Six months after surgery,the patient  is under HC, showing a remarkable clinical improvement and normal BP - without requiring antihypertensive drugs.

LH, FSH, PRL, To, TSH, T4, IGF1 and routine laboratory studies are normal.

CONCLUSIONS:

1-    In our patient, the 8mg-DXM test showed no inhibition and CD diagnosis was confirmed by IPSS.

2-    The dissociation between MRI image (left) and IPSS response (right) posed the question as to which side should be approached. A predominance of the right sinus drainage over the left and/or the existence of contralateral drainage could account for this dissociation-among other factors.

3-    The clinical and laboratory remission after resection of the left microadenoma would suggest a better correlation with MRI than with IPSS for the lateralization of pituitary microadenoma. The long-term outcome will allow us to evaluate this assumption.

 

Nothing to Disclose: EMP, LLG, FF, FL, AC, PS, AR