Rare case of renal Ewing sarcoma presenting as ectopic Cushing syndrome in a 12-year-old girl.

We present a 12-year-old girl with recent onset weight gain and purple striae over the abdomen. Examination revealed her to be hypertensive. On evaluation for Cushing syndrome (CS), her cortisol and adrenocorticotropic hormone (ACTH) were found to be high. MRI brain showed a suspicious lesion (thought to be pituitary microadenoma). Inferior petrosal sinus sampling was not conclusive of pituitary source of ACTH. High dose dexamethasone suppression test confirmed an ectopic source of ACTH secretion and CT scan revealed a mass in the right kidney which was laparoscopically excised. Histopathology and immunohistochemistry confirmed Ewing sarcoma. Our case highlights the rare presentation of renal Ewing sarcoma (RES) as CS. To the best of our knowledge, this is only the second case report of RES/primitive neuroectodermal tumour of the kidney presenting as CS in paediatric age group and first with a concomitant pituitary incidentaloma.