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This Article Accepted manuscript (PDF) All Versions of this Article: EJE-08-0385v1 159/4/483    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Burman, P. Articles by Sundin, A. PubMed PubMed Citation Articles by Burman, P. Articles by Sundin, A.

Dual bronchial carcinoids and Cushing's syndrome with a paradoxical response to dexamethasone and a false positive outcome of inferior petrosal sinus sampling

P Burman, Department of Endocrinology, University Hospital, Malmo, Sweden
A Lethagen, Department of Endocrinology, University Hospital, Malmo, Sweden
K Ivancev, Department of Radiology, University Hospital, Malmo, Sweden
L Johansson, Department of Pathology, University Hospital, Malmo, Sweden
A Sundin, Department of Diagnostic Radiology, University Hospital, Uppsala, Sweden

Correspondence: Pia Burman, Email: Pia.A.Burman{at}skane.se

Abstract

Objective Establishing the cause of Cushing's syndrome can be a considerable challenge, in particular in ectopic ACTH syndrome, and often requires a combination of biochemical tests and imaging procedures.

Subject A 27-year-old man presented with signs of Cushing's syndrome. P-ACTH levels were 3 times above the ULN and free urinary cortisol in the order of 1900 nmol/24 h. The work-up showed remarkable results.

Results A 2-day low-dose dexamethasone suppression test demonstrated paradoxical increases in cortisol. Sampling from the inferior petrosal sinuses (BIPSS) showed a central to peripheral ACTH ratio of 4.7 after CRH stimulation, i.e. indicated pituitary disease, but MRI of the pituitary was normal and baseline P-CRH <1.0 (ref. <5) pmol/L. CT scan of the lungs showed 2 oval-shaped masses, 1.3 x 1.8 and 1.3 x 2 cm, in the middle lobe. Both were positive at somatostatin receptor scintigraphy, compatible with tumors or inflammatory lesions. Subsequently, 11C-5-hydroxytryptophan-PET showed distinct uptake in the tumors but not elsewhere. Two carcinoids situated 3 cm apart, both staining for ACTH, were removed at surgery.

Conclusion This unusual case with dual bronchial carcinoids inducing hypercortisolism illustrates the problems with identifying the source of ACTH in Cushing s syndrome. Possibly, the false positive result at BIPSS reflects an unusual sensitivity of the pituitary corticotrophs to CRH in this patient since ectopic CRH secretion and/or eucortisolism at the time of the procedure could be ruled out. The work-up illustrates the great value of 11C-5-hydroxytryptophan-PET as a diagnostic procedure when other investigations have produced ambiguous results.