ACTH-dependent Hypercortisolemia in a Patient with a Pituitary Microadenoma and an Atypical Carcinoid Tumour of the Thymus

Diagnostic performance of various imaging modalities in localizing ectopic ACTH syndrome: A systematic review

BACKGROUND

To elucidate the role of various imaging modalities for tumor localization in ectopic ACTH Cushing's syndrome (EAS).

DESIGN AND METHOD

Systematic review of the literature published between January 2015-2024 was performed. Patients (290 EAS patients, 23.8% Occult) who underwent contrast enhanced CT (CECT) and at least one PET/CT-scan (68Ga-SSTR, FDG and/or F-DOPA) were included.

RESULTS

The sensitivity for identifying EAS tumor was comparable across CECT (63.1%, n=290), SSTR-PET/CT (58.2%, n=187), and FDG-PET/CT (57.6%, n=191), but was poor for DOPA-PET/CT (30.8%, n=26). Sensitivity for detecting metastasis was also comparable across CECT (78%, n=73), SSTR-PET/CT (85.3%, n=41), and FDG-PET (73.7%, n=38). For localised lesions, sensitivity as per etiology and grade of NET were similar for three scans, with exception of Thymic NET and grade 1 NET where CECT was better than FDG PET/CT. In patients not localised on CECT, sensitivity of SSTR PET/CT was 33.3% (vs. 18.9% FDG-PET/CT) whereas for patients negative on CECT and FDG-PET, sensitivity of SSTR-PET/CT was 15%. In cases where CECT and SSTR-PET/CT failed to localize, the sensitivities of FDG-PET/CT and DOPA-PET/CT were only 5.7% (2/35) and 0% (0/9), respectively. SSTR-PET/CT has a distinct advantage with significantly lesser false positive (FP) lesions (2.6%, mostly in thyroid/or pancreas). In comparison, CECT and FDG-PET/CT had FP ∼11% (mostly in lung and/or mediastinum), most of which were negative on SSTR-PET/CT.

CONCLUSIONS

As per the current evidence, SSTR-PET/CT can be considered as the scan of choice in EAS evaluation, and further research is needed as one-fourth of the lesions remain occult.

Case report: A challenging case of severe Cushing's syndrome in the course of metastatic thymic neuroendocrine carcinoma with a synchronous adrenal tumor

Ectopic ACTH syndrome (EAS) remains one of the most demanding diagnostic and therapeutic challenges for endocrinologists. Thymic neuroendocrine tumors account for 5%-10% of all EAS cases. We report a unique case of a 31-year-old woman with severe EAS caused by primary metastatic combined large-cell neuroendocrine carcinoma and atypical carcinoid of the thymus. The patient presented with severe hypercortisolemia, which was successfully controlled with continuous etomidate infusion. Complex imaging initially failed to detect thymic lesion; however, it revealed a large, inhomogeneous, metabolically active left adrenal mass infiltrating the diaphragm, suspected of primary disease origin. The patient underwent unilateral adrenalectomy, which resulted in hypercortisolemia resolve. The pathology report showed an adenoma with adrenal infarction and necrosis. The thymic tumor was eventually revealed a few weeks later on follow-up imaging studies. Due to local invasion and rapid progression, only partial resection of the thymic tumor was possible, and the patient was started on radio- and chemotherapy.

Ectopic Cushing's syndrome due to thymic neuroendocrine tumours: a systematic review

Knowledge of ectopic Cushing's syndrome (CS) due to thymic neuroendocrine tumours (NETs) comes from short series or single cases. Our aim is to perform a systematic review using PubMed, Embase, Scopus, Ovid Medline and Biosis Previews of all cases with ectopic CS due to thymic NETs reported in the last 40 years and describe one illustrative patient attended in our institution. Search of literature: From 162 patients, 58.6% were male and mean age was 34.6 ± 13.9 years-old. Median of symptoms until diagnosis was 6 [2-24] months and 62% had aggressive CS. Imaging was positive in 93.7% (chest X-ray), 97.8% (computed tomography), 80.7% (somatostatin receptor scintigraphy) and median tumour size was 47 [25-68.5] mm. At presentation, 18% had localized disease, 26.2% locally invasive and 55.7% advanced. Eighty-eight present underwent surgery and histological subtypes were atypical (46.7%), typical (30.4%) and carcinoma (21.7%). Tumour persisted or recurred in 70.1%, 63% received radiotherapy and 45.2% chemotherapy. Follow-up median was 26.6 [14.5-57.5] months and mortality was reported in 35.8% with median survival of 38 [19-60] months. MEN-1 mutation was referred in 3.1%. Comparatively, carcinomas had aggressive CS more frequently while atypical showed advanced disease more often. In conclusion, thymic NETs causing ectopic CS are presented as aggressive hypercortisolism in the middle aged population. The disease is commonly extended at diagnosis and persists or recurs after surgery in most patients with a short term high mortality.

Long-term effect of everolimus in recurrent thymic neuroendocrine neoplasia

PURPOSE

Neuroendocrine neoplasia (NEN) of the thymus is a very rare entity with a poor prognosis. None of the treatments was proofed by studies. Usually, therapy protocols for bronchopulmonary carcinoids are used. So far no data exist on the effect of mammalian target of rapamycin (mTOR) inhibitors. We describe our long-term experience with everolimus and give a thorough review of the therapeutic strategies used so far.

PATIENTS AND METHODS

Four patients (mean age 46 years, range 37-55) with progressing thymic NEN (t-NEN) (two well-differentiated atypical carcinoids and two atypical carcinoids with large cell characteristics) were treated with everolimus 10 mg/day after the failure of at least one previous medical therapy. Everolimus was applied after a mean interval of 32.4 months (range 5-56) after the first diagnosis. The follow-up included clinical examination, imaging and chromogranin A testing in 3 or 6 monthly intervals.

RESULTS

We observed stable disease for a mean of 20.8 months. Both patients with large cell characteristics t-NEN (Ki-67 of 20%) had rapid progress after 7 and 10 months and had more previous therapies (three and six) than the patients with well-differentiated t-NEN (Ki-67 5% and 10%, progress after 24 and 42 months, one and two previous therapies). No severe side effects occurred. In three of four patients, everolimus led to stable disease for the longest compared to the other nonsurgical therapies used.

CONCLUSION

Comparing the sparse data available everolimus is a promising treatment for t-NEN at least in second-line therapy. A low Ki-67 index was associated with a better outcome.