ectopic kidney

Chest Mass in an Infant With Stridor

Michael W. Cater, MD

These chest radiographs (Figures 1 and 2) were obtained from a 2-month-old boy who was admitted to the hospital for evaluation and management of inspiratory stridor, which had begun at 4 to 6 weeks of age. The films showed a mass in the left side of the infant’s chest.

On admission to the hospital, the infant had clinical findings consistent with mild laryngomalacia characterized by mild inspiratory stridor, normal voice quality, and normal oxygen saturation.

Another significant finding on physical examination was hypospadias, with the urethra emerging on the underside of the glans penis. The testes were normal.

radiograph

How do you read these images?

A.Neuroblastoma

B.Congenital cystic adenomatoid malformation

C.Thoracic ectopic kidney

D. Pulmonary sequestration

(Answer and discussion on next page)

Answer: C, thoracic ectopic kidney

Based on the radiographs and clinical presentation, the infant received a diagnosis of left thoracic ectopic kidney.

Thorough radiologic evaluation showed the child’s right kidney to be anatomically normal. Both kidneys were shown to be functioning normally, with no evidence of vesicoureteral reflux.

After discharge from the hospital, the patient underwent surgical repair of his hypospadias at 6 months of age. The child is now 3 years of age, and his laryngomalacia has totally resolved. His urologic status remains normal.

Discussion

Renal ectopia is relatively common, with a prevalence of approximately 1 in 900 people.1 However, a thoracic ectopic kidney is a very rare developmental anomaly and is the rarest form of renal ectopia. Campbell’s historic 1930 report on the results of nearly 16,000 autopsies of children found only a single case of intrathoracic kidney among 22 cases of renal ectopia.2 Wolfromm in 1940 was the first to describe an intrathoracic kidney in a living patient, a 43-year-old woman.3 Between 1987 and 2012, only 13 cases of intrathoracic kidney were reported in the pediatric age group.4

Burke and colleagues in 1967 compiled a list of 31 cases of intrathoracic kidney.5 They found the left kidney to be most commonly ectopically situated, and they described no case of bilateral ectopic kidneys. The patient’s sex was known in 17 of the 31 cases; 15 were male. The intrathoracic kidneys were asymptomatic, and in all cases, their function was unimpaired.5

Renal ectopia usually is discovered incidentally on chest radiographs.5-7 Recently, Lee and colleagues reported a case of intrathoracic kidney diagnosed prenatally via ultrasonography.8

Cases of isolated intrathoracic kidney in children, without evidence of bowel herniation, can be safely managed nonsurgically with observation alone,4 as was the case with this patient. The ectopic kidney usually is asymptomatic, although associated urologic abnormalities can occur in children, such as our vesicoureteral reflux, contralateral renal dysplasia, cryptorchidism, and (as in our patient) hypospadias.9 

Michael W. Cater, MD, is a pediatrician at Pediatric & Adult Medicine Inc in Tustin, California.

William Yaakob, MD—Series Editor, is a radiologist in Tallahassee, Florida.

References

1. Bauer SB. Anomalies of the upper urinary tract. In: Wein AJ, Kavoussi LR, Novick AC, Partin AW, Peters CA, eds. Campbell-Walsh Urology. Vol. 4. 9th ed. Philadelphia, PA: Saunders Elsevier; 2007:3269-3303.

2. Campbell MF. Renal ectopy. J Urol. 1930;24:187-189.

3. Wolfromm G. Position of kidney in right diaphragmatic eventration. Mem Acad Chir (Paris). 1940;66:41-47.

4. Murphy JJ, Altit G, Zerhouni S. The intrathoracic kidney: should we fix it? J Pediatr Surg. 2012;47(5):970-973.

5. Burke EC, Wenzl JE, Utz DC. The intrathoracic kidney: report of a case. Am J Dis Child. 1967;113(4):487-490.

6. Mensah YB, Forson C. Left thoracic kidney: a rare finding at intravenous urography. Ghana Med J. 2010;44(1):39-40.

7. Aydin HI, Sarici SU, Alpay F, Gökçay E. Thoracic ectopic kidney in a child: a case report. Turk J Pediatr. 2000;42(3):253-255.

8. Lee S, Roh H, Joo W, Yoo H. P18.15: A case of thoracic kidney, prenatally diagnosed by ultrasonography. Ultrasound Obstet Gynecol. 2010;36(suppl 1):242.

9. Guarino N, Tadini B, Camardi P, Silvestro L, Lace R, Bianchi M. The incidence of associated urological abnormalities in children with renal ectopia. J Urol. 2004;172(4 pt 2):1757-1759.