DOI:10.2214/AJR.05.2145
AJR 2006; 187:W320-W321
© American Roentgen Ray Society
Crossed Ectopia of the Left Testis Detected on MRI
Rajesh Gothi and
Bharat Aggarwal
Dr. Diwan Chand Aggarwal Imaging Research Centre New Delhi 110001,
India
WEB—This is a Web exclusive article.
A 15-month-old boy was sent for MRI with a clinical diagnosis of
right-sided inguinal hernia and an impalpable left testis. MRI was performed
using conventional spin-echo sequences. The study revealed maldescent of the
left testis into the right hemiscrotum. A right-sided inguinal hernia, which
had been suspected clinically, included the abnormally descended left testis,
which was subsequently repositioned in the left hemiscrotum. The left testis
had its own distinct vas deferens and blood supply from the ipsilateral
side.
MRI highlighted the position of the two testes. Both testes were normal in
size, shape, and signal intensity (Fig.
1A). The left hemiscrotum was small and empty. No evidence was
seen of any persistent müllerian duct abnormality. We could not identify
the vas deferens or the testicular artery of the crossed testis on the
unenhanced MR images. However, we could see two discrete spermatic cordlike
structures that were better appreciated on the T1-weighted images
(Fig. 1B). Crossed ectopia,
also called "transverse testicular ectopia," is a rare anomaly in
which the testis is seen either in the contralateral inguinal canal or in the
hemiscrotum. Also named "testicular pseudoduplication,"
"unilateral double testis," and "transverse aberrant
testicular maldescent," crossed ectopia is a condition in which both the
gonads migrate toward the same hemiscrotum. The ectopic testis may lie in the
opposite hemiscrotum, in the opposite inguinal canal, or at the opposite deep
inguinal ring. An inguinal hernia is invariably present on the side to which
the ectopic testis has migrated. The vascular supply to the ectopic testis
originates from the appropriate ipsilateral side
[1].
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Fig. 1A —15-month-old boy with crossed ectopia of left testis detected
on MRI. Coronal T2-weighted image shows maldescent of left testis into right
hemiscrotum. Note both testes are of same size and have similar signal
intensity. Note also small left hemiscrotum.
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On the basis of the presence of various associated anomalies, transverse
testicular ectopia has been classified into three types: those associated with
inguinal hernia alone (40-50%), those associated with persistent or
rudimentary müllerian duct structures (30%), and those associated with
other anomalies without müllerian remnants—inguinal hernia,
hypospadias, pseudohermaphroditism, and scrotal abnormalities (20%)
[2].
Transverse testicular ectopia must be distinguished from testicular
duplication. Testicular duplication may result either from duplication of the
genital ridge or from longitudinal or transverse division of the genital
ridge. On the other hand, in a case of crossed ectopia, the ectopic testis
descends abnormally to the opposite side to lie with the normally descended
testis [3]. In the reported
cases of testicular duplication that mention size, the supernumerary testis is
said to be smaller than the normal one. Duplicated testes of equal size are
unusual. On the other hand, in transverse testicular ectopia, the testes are
of equal size. In testicular duplication, the testes have a common blood
supply and a common vas deferens. In crossed ectopia, the two testes have
separate sets of blood vessels and separate vasa deferens. Variations in the
anatomic position of the vas deferens and abnormalities of insertion of the
vas into the testis can occur, however.
The usefulness of radiologic evaluation in the detection of ectopic testis
remains controversial. However, because clinical examination of the scrotum is
difficult as a result of the small size of the testes and the epididymis in
infants and young children, and eliciting patients' history is challenging,
imaging of the scrotum in childhood is important. Sonography is the initial
method of choice for localizing the testis and confirming the clinical
findings. CT is not used frequently because of its radiation hazard, but it
does reveal the ectopic testis in the inguinal canal and pelvis.
MRI and MR venography [4]
are excellent for the preoperative location of transverse testicular ectopia.
In our patient, the basic spinecho sequences enabled us to detect the crossed
ectopic testis and to identify the two spermatic cords.
References
- Hafez A, Khoury AE. Crossed ectopic testis: another factor favoring
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- Gauderer MW, Grisoni ER, Stellato TA, Ponsky JL, Izant RJ Jr.
Transverse testicular ectopia. Pediatr Surg1982; 17:1
-2
- Sastry SC, Venkateswarlu K, Hussain BA. Transverse testicular
ectopia. Int Surg 1974;59
: 373-374[Medline]
- Lam WW, Le SD, Chan KL, Chan FL, Tam PK. Transverse testicular
ectopia detected by MR imaging and MR angiography. Pediatr
Radiol 2002; 32:126
-129[CrossRef][Medline]
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