Right renal cell carcinoma: venous collaterals to the duodenum masquerading as Mallory-Weiss syndrome.

Haematemesis is an uncommon manifestation of renal cell carcinoma (RCC). This case report describes a woman in her late 60s who presented with haematemesis, melena and hypovolemic shock. Initial ultrasonography revealed a well-defined, upper-polar right kidney mass. Upper gastrointestinal endoscopy identified a Mallory-Weiss tear, treated with epinephrine injection. However, persistent haematemesis and haemoglobin drop necessitated further investigation.A CT abdominal angiogram identified an arteriovenous fistula (AVF) originating from the renal mass, supplied by branches of the main renal artery and an accessory artery. The fistula traversed the second part of the duodenum, maintaining a fat plane, with active contrast extravasation.Angioembolisation of feeding arteries stabilised her condition, which was then followed by a right radical nephrectomy and ligation of the AVF. Histopathology confirmed clear cell renal cell carcinoma (pT2aNx). This is the first documented case of RCC presenting as haematemesis due to venous collaterals into the duodenum.