A Challenging Case Of A Severe Ectopic Cushing Syndrome Due To Recurrent Thymic Carcinoid Tumour

Introduction: Cushing syndrome due to thymic carcinoids is rarely seen. Severe Cushing syndrome is an endocrine emergency requiring prompt treatment initiation. Here, we report a case of severe Cushing syndrome due to a thymic neuroendocrine tumour.Case Description: A 60-year-old female presented with symptomatic severe hypokalaemia. She didn’t have the typical cushingoid appearance, but dark pigmentation was evident over the knuckles and nails. She had severe hypokalaemia (2.2 mmol/L). Further assessment confirmed the diagnosis of ACTH-dependent Cushing syndrome. Ten years back, she underwent surgery for thymic atypical carcinoid tumour followed by chemoradiation. History revealed probable Cushing syndrome during that period, but medical record was not available. Considering this, CECT Chest, Abdomen and Pelvis was arranged, and it showed recurrence of invasive thymic neoplasm. Histology was atypical thymic carcinoid with synaptophysin positivity. Diagnosis of severe ectopic Cushing syndrome was made with cortisol burden of up to 1500 nmol/L with refractory hypokalaemia worsening glycaemic control and high blood pressure. The multidisciplinary team decision was to do urgent bilateral adrenalectomy. She underwent bilateral adrenalectomy after preoperative reduction of cortisol with etomidate infusion. Unfortunately, her post-operative course was complicated with severe COVID pneumonia with secondary bacterial sepsis, and she succumbed to death after 3 weeks of surgery.Conclusion: Ectopic Cushing syndrome is well-known to cause severe hypercortisolism with catastrophic complications. Emergency bilateral adrenalectomy is a safe option in this situation, especially when the primary tumour is not identified or can’t be resected completely within a short time. Increased risk of infection persists even after cortisol reduction with surgery and appropriate infection control measures and surveillance are of paramount importance.