RCC in cross ectopic kidney: a challenging case
The present case has been reported in BMJ.

A 57-year-old woman with a 5-month history of left-upper quadrant (LUQ) abdominal pain was referred after a retroperitoneal mass was discovered on CT scan of the abdomen and pelvis. Clinical history revealed mild LUQ abdominal pain over the course of 5 months, associated with anorexia, unintended weight loss and several episodes of painless gross haematuria. Physical examination was positive for an ill-defined mass in the LUQ extending to the umbilical region. Routine laboratory tests did not reveal abnormal findings except for microscopic haematuria.

CT scan images revealed a left cross ectopic kidney fusing laterally with the lower pole of right kidney in addition to a mass measuring 7.5×8.5 cm emerging from the ectopic kidney. The mass extended to the left flank crossing the abdominal aorta and passing behind the inferior mesenteric artery. This structure mimicked a horseshoe kidney.

Retrograde pyelography confirmed the presence of cross ectopic left kidney with a mild hydronephrosis without evidence of ureter obstruction. Partial nephrectomy was performed through a left subcostal transperitoneal approach. Pathology confirmed the diagnosis of papillary renal cell carcinoma (RCC).

Postoperative course was complicated by mild urinary extravasation which was successfully managed by the placement of double J (DJ) catheters.

Learning points
• Renal ectopia is a developmental anomaly characterised by abnormal anatomical location of one or both of the kidneys.

• Diagnosing neoplasms in renal ectopia can be challenging and might mimic radiologically and clinically other renal anomalies, including horseshoe kidney.

• Although most patients remain asymptomatic, ectopic kidneys carry increased risk of urinary calculus formation as well as hydronephrosis.

• Preoperative vascular evaluation combined with transperitoneal approach save time and decrease risk of surgical complications.

Read more here: http://casereports.bmj.com/content/2018/bcr-2018-226879.full