Endocrine Abstracts

Introduction

Paraneoplastic Cushing syndrome (CS) due to ectopic ACTH secretion is a rare syndrome usually associated with severe hypercortisolism which is responsible for life-threatening comorbidities. These tumors are often difficult to locate. Among all ACTH-secreting thoracic tumors, well differentiated neuroendocrine tumors located in the bronchi are the most common and account for 20% to 40% of all cases.

Case

A 36-year old man, was admitted on June 2020 for exploration of a CS. His medical history dates back to July 2019 with the diagnosis of insulin-requiring diabetes and a resistant severe hypertension with symptomatic hypokalaemia, all associated with morphological changes suggesting a CS. The drug history excluded an exogenoous exposure to glucocorticoids. Clinical examination revealed facio-truncular obesity, thin arms and legs, muscular atrophy, «moon face», buffalo neck, steroid acne on the trunk, fragile and poorly healing skin, large violaceous striae over the abdomen and axillary area, spontaneous bruising.Biochemical findings confirmed the diagnosis of CS: urine free cortisol was elevated (3880 µg/24 hover 53 times of normal); the circadien cortisol secretion was disturbed. Adrenocorticotropic hormone (ACTH) level was high (254.5 ng/ml five times normal). Clinical assessement for complications(in addition to diabetes and hypertension) found a left ventricular hypertrophy, dyslipidemia, functional hypogonadism, diffuse bone demineralization, chronic hypocalcemia, hypercoagulability, anxious and depressive symptomatology with insomnia. Based on the rapid deterioration of our patient’s general condition, severity of clinical manifestations, a negative nocturnal 8 mg-DST( cortisol level: 421 µg/l)and a negative pituitary imaging, an ectopic CS was suspected.Thus, a chest CT-scan had shown a solid peripheral nodule of the postero-basal segment of the right lung of 20 mm with heterogeneous enhancement on injection of iodinated contrast agent, suggesting a neoplasic origin. Due to the unavailability of octreoscan preoperatively as well as the severity of clinical and biological signs resisting to medical treatment, the patient was operated.He underwent a video-assisted thorocoscopic surgery with total resection of the tumor. Histological examination revealed a low grade pulmonary neuroendocrine tumor measuring 17 mm. Tumor cells were positive for chromogranin, synaptophysin and ACTH on immunohistochemistry. Post-operative evolution was marked by improvement of diabetes and hypertension, normokaliemia and adrenal insufficiency was obtained within the second week.Octreoscan performed after the surgery did not show a metastatic localisation or residual tumor. We observed that physical features were ameliorated at 3 months and resolved at 6 months.

Conclusion

Ectopic ACTH secreting tumors are rare and severe. The ideal treatment is their excision. In addition to symptomatic treatments, hypercortisolism must be controlled rapidly as a pre-operative management or if surgery is impossible. However, these tumors carry an excellent prognosis especially localized and well-differentiated bronchial tumors.