A rare case of ectopic ACTH syndrome with rhabdomyolysis

Is Ectopic Cushing Syndrome Commonly Associated with Small Cell Lung Cancer (SCLC)? Critical Review of the Literature and ACTH Expression in Resected SCLC

The literature emphasizes that pulmonary ectopic Cushing syndrome (ECS) is associated not only with neuroendocrine tumors (NETs), but also with small cell lung carcinomas (SCLCs). This statement is debatable, because extrapulmonary ECS is associated with NETs in the vast majority of cases and very rarely with neuroendocrine carcinomas (NECs). Therefore, we critically reviewed the literature on SCLCs associated with ECS (ECS-SCLC) and performed immunohistochemical analysis of ACTH expression in 155 resected SCLCs and 158 pulmonary NETs. The literature search revealed that 90% of the 205 ECS-SCLC patients identified between 1952 and 2023 had no or poor-quality histologic images, so the diagnosis of SCLC could not be confirmed. Review of the 20 reports (10%) with histologic images revealed that 18/20 (90%) had to be reclassified as "probable NET", of which 5/18 (28%) showed spindle cell morphology, while only 2 cases were qualified as "SCLC compatible" due to their pleomorphic cell features. Immunohistochemically, 5/155 (3%) resected SCLCs, all without ECS, showed weak single cell ACTH expression, whereas in the NET cohort, 61/158 (39%) tumors expressed ACTH, of which 4 (3%) were associated with ECS. Both observations, the literature review, which casts doubt on previously reported data regarding the frequency of SCLC in ECS, and the immunohistochemical study, suggest that there is limited evidence that SCLC is the cause of ECS.

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.

Management of small cell lung cancer complicated with paraneoplastic Cushing's syndrome: a systematic literature review

Paraneoplastic Cushing's syndrome (PCS) is a rare, but clinically important feature of small cell lung cancer (SCLC) that is associated with even worse prognosis. To identify key considerations in comprehensive management of SCLC patients complicated with PCS, we conducted a systematic review of relevant reports on PubMed and Web of Science, focusing on SCLC with PCS cases. The systematic review analyzed 61 reports published between 1985 and 2022 with a total of 157 SCLC patients included. Out of the 157 patients, 132 (84.1%) patients across 58 (95.1%) reports were diagnosed with ectopic Cushing's syndrome. The immunohistochemical (IHC) staining for adrenocorticotropic hormone (ACTH) was performed on 30 (19.1%) patients across 22 (36.1%) reports and demonstrated encouraging performance. For treatment, chemotherapy and ketoconazole were utilized in 50 (81.97%) and 24 (39.34%) reports, respectively. Regarding cause of death, infection and cancer were equally frequent, each being recorded in 17 (27.87%) reports. To conclude, the majority of PCS cases in SCLC patients were caused by ectopic hormone secretion. In order to make a differential diagnosis, it is recommended to utilize IHC staining for a specific hormone such as ACTH or corticotropin-releasing hormone. In the comprehensive treatment of SCLC with PCS patients, effective management of hypercortisolism and potent safeguarding against infection play two crucial roles. Ultimately, further confirmations are required regarding the specificity and accuracy of IHC staining technique as well as the efficacy and safety of immunotherapy in the treatment of SCLC with PCS patients.