this report is of a bilobed testicle in a 12-year - old boy , which presented as an atypical testicular mass .
it is thought to be a variant of polyorchidism , which is associated with an increased risk of malignancy and testicular torsion . due to the extremely rare nature of bilobed testes
, it is important to report our findings and start to gather information on the long - term outcome of this condition .
a 12-year - old boy was referred by his gp to the paediatric surgery clinic in a district general hospital with a 6-week history of a lump near the inferior pole of his left testicle .
it was non - tender , non - erythematous and had not changed in size or consistency .
he was otherwise fit and well , with no family history of urological disorders . on examination , his abdomen was soft and non - tender , with a normal right testis and right spermatic cord .
a smooth well - defined lump was palpated on the inferior pole of the left testis .
ultrasound demonstrated that both testicles were of a similar size , with normal vascularity and normal epididymi .
the palpable lump corresponded to a well - defined 1-cm mass attached to the lower pole of the left testicle ( fig .  1 ) .
it had a similar echo pattern to the testicle with normal vascularity ( fig . 
a mass is seen attached to the left testicle with the same echo pattern as the normal testicular tissue . 

a mass is seen attached to the left testicle with the same vascularity as surrounding testicular tissue .
a mass is seen attached to the left testicle with the same echo pattern as the normal testicular tissue .
a mass is seen attached to the left testicle with the same vascularity as surrounding testicular tissue .
the size of the lump was unchanged , although he now reported intermittent pain and swelling of the lump .
he was referred to a consultant paediatric urologist and his testicle rescanned 6 months after his initial presentation .
he will be reviewed again in 12 months , with a view to discharging him if no further changes are seen .
of the five previously reported cases of a bilobed testicle , four are in children aged from 3 to 13 [ 14 ] with the other occurring in a 30-year - old man who had been symptomatic for 10 years .
a bilobed testicle is thought to represent an incomplete division of the genital ridge by peritoneal bands during the development of the testis from 6 weeks of embryological life .
ultrasound and mri imaging of polyorchidism have demonstrated that the combined length of a supernumerary and ipsilateral testicle are the same as the contralateral testicle , supporting this theory .
due to the larger number of case reports in comparison with a bilobed testicle and the presumed similar aetiology , we are reliant on the literature on polyorchidism when considering the management of a bilobed testicle .
the risk of malignancy in a supernumerary testicle is reported between 5.7 and 7% , in comparison with 6 in 100 000 in the general population and 24 in 100 000 in cryptorchidism .
there are no published cases to date of malignancy associated with a bilobed testicle and the reported cases of malignancy have occurred when the supernumerary testicle was found in a non - scrotal position . consequently , whilst an increased risk of malignancy is possible , the evidence is insufficient to advocate surgical management .
a testicular tumour should be considered as a differential diagnosis of any scrotal mass . in view of the normal testicular architecture and vascularity on ultrasound ,
we excluded a tumour in our patient due to the high sensitivity of ultrasound . consequently , tumour markers such as alpha - fetoprotein and beta - human chorionic gonadotropin were not measured .
spermatogenesis is normal in 50% of supernumerary testicles   and it is likely that this figure  is higher for bilobed testicles .
a growing number of case reports suggest that conservative management with regular follow - up and imaging is appropriate for polyorchidism with normal echotexture on ultrasound and uncomplicated cases of bilobed testis [ 1 , 2 , 57 ] .
a review published in 2004 found the risk of testicular torsion of a supernumerary testicle to be 15% , in comparison with 0.025% of the general population and 0.25% in cryptorchidism .
of the five reported cases of bilobed testis , one case presented with torsion resulting in orchidectomy .
they must know the signs and symptoms of torsion and be encouraged to present early if it is suspected . unlike cryptorchidism , surgery is not otherwise required for a bilobed testicle and therefore orchidopexy is not appropriate for uncomplicated cases . in our case ,
however , he was asymptomatic when examined with no ultrasound changes and so it was not felt that orchidopexy was indicated .
regular hospital appointments can produce unnecessary distress and concern for the patient and their family .
if no changes are seen in a further 12 months , our patient will be discharged to primary care .
self - examination of the testicle may be challenging due to the distorted anatomy but should be advocated to detect early changes .
ultrasound must be undertaken promptly if there is any concern about changes to the testicle .
monitoring tumour markers may be appropriate in non - scrotal polyorchidism due to the significantly increased risk of malignancy .
as the current literature does not provide strong evidence of malignancy associated with bilobed testis , it should not be advocated for this condition .
conservative management appears to be appropriate in uncomplicated cases such as the one we present .
it is unclear how the risk of torsion and malignancy in polyorchidism is applicable to a bilobed testicle .
the risk of unnecessary surgery needs to be balanced against the risk of these serious complications .
it is important that any long - term complications are reported to further our knowledge of this extremely rare condition .
 a bilobed testicle is an extremely rare congenital malformation , with only five cases published to date . 
 we present the case of a 12-year - old boy with a bilobed testicle . 
 with so few cases available , much of what is known about the management of this condition is based on cases of polyorchidism and the complications associated with this , including malignancy and torsion . whilst surgery may play a role in some patients , uncomplicated cases can be managed conservatively . 
 there is no long - term data on the outcome of conservative management but we propose this patient can be discharged if no further changes are identified after 18 months . 
INTRODUCTION
CASE REPORT
DISCUSSION