Finding the Culprit: Cushing Syndrome Secondary to Lung Carcinoid Tumor

Cushing syndrome resulting from ectopic adrenocorticotropic hormone (ACTH) secretion (EAS) is a rare condition, and its occurrence in adolescents is even more uncommon, representing <1% of cases. We describe a case of EAS from a lung carcinoid tumor leading to Cushing syndrome in a young woman, which was successfully treated with excision of the tumor.

An 18-year-old woman presented with mood disturbances, weight gain, and fatigue for 6 months. Workup revealed high levels of urinary free cortisol (>900 μg/dL; normal range, <45 μg/dL) and midnight salivary cortisol (0.755 μg/dL; normal range, <0.09 μg/dL). The ACTH and cortisol levels remained elevated after a low-dose dexamethasone suppression test. Magnetic resonance imaging of the pituitary gland did not reveal any adenoma and inferior petrosal sinus sampling showed no central-to-peripheral gradient. A diagnosis of EAS was made. Subsequent body imaging noted a 1-cm lung nodule. Due to symptoms of severe hypercortisolism including hypokalemia and worsening mood changes, the patient was started on metyrapone as a bridge to surgery. A few weeks later, the patient underwent successful surgical resection, after which symptoms promptly resolved. Pathology report later confirmed an atypical lung carcinoid tumor. The patient remained in remission at 1-year follow-up.

Medical therapy aids in managing severe hypercortisolism in ACTH-secreting tumors until definitive surgical treatment can be undertaken.

This case underscores the critical importance of promptly recognizing EAS and the resulting severe hypercortisolism symptoms because early surgical intervention can lead to a cure.