We present the interesting and complex case of a young girl with neonatal left renal vein thrombosis, who became hypertensive at the age of 4 years, without evidence of target organ damage. Ultrasound and radiolabelled dimercaptosuccinic acid (DMSA) scintigraphy showed a single functioning right kidney, with the presumption that the left kidney had involuted after its neonatal insult. The origins of her hypertension remained elusive over the subsequent 6 years despite extensive investigation into secondary causes. The single abnormality was a mild elevation in her plasma renin to 5.6 pmol/ml/hour (normal range < 4.5 pmol/ml/hour). She required treatment with two antihypertensive agents in order to control her blood pressure. She experienced troublesome side effects attributable to both medications. Her course was complicated by autoimmune thyroid disease for which she received hormone replacement. A routine ultrasound of her renal tract at 9 years of age co-incidentally identified a large pelvic mass. Further imaging was undertaken with contrast-enhanced magnetic resonance imaging (MRI) and surprisingly, a left renal remnant was also identified. She underwent right oophorectomy and mass excision, with histology confirming a diagnosis of mature ovarian teratoma. After 10 months, laparoscopic removal of her left kidney remnant was performed and within 2 weeks, she was able to be weaned off her anti-hypertensive medication. She has remained normotensive over the course of her subsequent follow-up.
There is only one other case report in the literature that similarly suggests that MRI may be a useful tool in identifying atrophic, non-functioning kidneys in hypertensive children with a single kidney on ultrasound. Our case would further support the use of this imaging modality in this cohort of patients.
Conclusion We support a role for the early use of MRI in order to detect occult renal tissue in children with a single kidney who are hypertensive without cause. We also highlight the importance of considering that the DMSA scan will not always identify occult renal tissue capable of producing clinical effects.