Endocrine Abstracts

During the evaluation of hypercortisolism, distinction between Cushing’s disease (CD) and ectopic ACTH syndrome (EAS) may be problematic. Detailed medical history, diagnostic procedures and pitfalls associated with EAS of four cases are presented. All the four patients had ectopic Cushing’s syndrome due to typical bronchial carcinoids. Their mean age was 39 years, and the mean time from the presentation of Cushing’s symptomes until diagnosis and definitive cure was 2.3 years (from 9 months to 5 years). The high-dose dxm suppression test was misleading in Cases 1 and 2, indicating CD. In Case 2, bilateral inferior petrosal sinus sampling (BIPSS) indicated a central source of ACTH overproduction, which led to hypophysectomy, despite of negative sella MRI findings. In Case 3, the BIPSS results were inconclusive and the sella MRI scan was negative, so renewed search for an ectopic origin was decided. In Case 4, the cortisol response to high-dose dxm was negative, but on the sella MRI pituitary microadenomas were visible. This led to a retrospectively unnecessary hypophysis surgery.

¹¹¹In-octreotide SPECT correctly localized lung carcinoid in every case. Hybrid imaging using SPECT–CT allowed an accurate anatomic description, detection of additional sites of disease, and higher specificity by exclusion of false-positive uptake at sites of physiologic tracer activity.

Conclusion: ¹¹¹In-octreotide SPECT-CT was the most valuable and decisive method in the detection of ectopic ACTH-secreting tumors. A more favorable place in the diagnostic algorithm of ACTH-dependent hypercortisolism should be considered for such an image-fusion method applying simultaneous SPECT and CT acquisitions.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.