ESPE Abstracts

Paraneoplastic Cushing syndrome is extremely rare. To date, there are few reported cases related to Wilms' tumor. We describe a patient who presented with Cushing syndrome and was subsequently found to have Wilms' tumor. Our patient is a 9 year-old boy, who presented with hyperphagia and excessive weight gain for 3 months. His abdomen was also progressively bigger. There was no ingestion of steroids or traditional medication. Subsequently he sought medical advice because of persistent cough and was found to be hypertensive with features of Cushing syndrome. On physical examination, his height was 123cm (50-75^thcentile) and his weight was 32.3kg (90-97^thcentile). He had features of Cushing syndrome with moon-like facies and buffalo hump. There was a firm ballotable mass in the left upper quadrant region. A Computed Tomography of the abdomen revealed a 9.2 x 12.7 cm mass arising from the upper pole of the left kidney likely to be Wilms' tumor. The adrenal glands could be visualized and looked normal. We proceeded to perform a low dose dexamethasone suppression test followed by high dose dexamethasone suppression test. The low dose dexamethasone suppression test confirmed the diagnosis of Cushing syndrome (not adequately suppressed). His cortisol level was suppressed during high dose dexamethasone test which suggest pituitary Cushing disease. However, his Magnetic Resonance Imaging of the pituitary gland was normal. His ACTH level was 9.2 pmol/L. The patient underwent a left radical nephrectomy and partial adrenalectomy. He was covered with stress dose of hydrocortisone peri-operatively. Biopsy showed Stage I Wilms' tumor (Blastemal predominant). Immmunohistochemistry for ACTH was negative in the tumor cells. We were not able to perform immunohistochemical studies for CRH. His hydrocortisone was eventually weaned off. By a year after the operation, he was back to his normal habitus, and there was no clinical feature of Cushing syndrome. The resolution of Cushing syndrome after the Wilms' tumor was treated showed that this was likely a case of paraneoplastic Cushing syndrome. The challenge lies in the diagnosis and the management of steroid therapy post-operatively. We also highlighted the patient's peculiar cortisol secretory pattern and his response to both dexamethasone suppression tests.