Pubic Accessory Scrotum: a Case Report of a Rare Position

Scrotum shows multiple congenital anomalies which could be explained by embryological abnormalities in migration of labioscrotal swelling. Our case was a neonate who had an accessory scrotum in the pubic area at delivery which is a rare position. Ultrasound scan and voiding cystourethrography showed adequate capacity, shouldering and smooth outline with insignificant mild residual urine of bladder, and dilated posterior urethra. Magnetic resonance imaging revealed a pubic accessory scrotum with thickened skin and subcutaneous tissue with no detectable internal contents or pelvic connection; however, pelvicalyceal system was dilated suggesting pelviureteric junction obstruction. Excision of accessory scrotum was discussed with parents but they refused. Ultrasound follow-up of the associated congenital hydronephrosis revealed improvement of hydronephosis.


Introduction
Accessory scrotum is a rare congenital anomaly [1]. A normally developed scrotum could be associated with ectopic scrotal tissue which may be detected in the perineum, groin, or elsewhere but usually without containing testes within [2,3]. It may be an isolated anomaly or in association with others either anorectal or genitourinary anomaly which mandates further imaging. Herein, we illustrate a rare case of pubic accessory scrotum with other genitourinary anomalies in the form of pelviureteric junction obstruction.

Case Report
Our case was a neonate who had an accessory scrotum with a rare position in the pubic area discovered at delivery (Fig. 1). Ultrasound scan showed moderate hydronephrosis of the left kidney measuring about 19.9 mm with turbidity within. Consequently, voiding cystourethrogram was done showing dilatation of the posterior urethra but with a normal caliber of the anterior urethra excluding the diagnosis of a posterior urethral valve. Additionally, adequate capacity, shouldering, and smooth outline with mild residual urine of bladder were detected (Fig. 2).
Magnetic resonance imaging revealed an accessory scrotum with thickened skin and subcutaneous tissue with no internal contents or pelvic connection in the pubic area; however, the pelvicalyceal system was dilated with a faint left ureter suggesting pelviureteric junction obstruction (Fig. 3). The pregnancy was uneventful, and there was no a history of exposure to any teratogens. Excision of the accessory scrotum was discussed with both parents but they refused. Ultrasound follow-up of the associated urological anomalies revealed improvement of hydronephrosis without any further dilatation of the renal pelvis.

Discussion
Scrotal anomalies which are extremely rare include four types: bifid scrotum, penoscrotal transposition, ectopic scrotum, and accessory scrotum. Over the literature, there are 52 patients of an accessory scrotum. A perineal lipoma was associated in 37 patients (71%), whereas perineal lipoblastoma was detected in three patients (6%) and an isolated accessory scrotum was observed in twelve patients without lipoma or lipoblastoma [4,5].
Bifid scrotum is defined as a partial or complete separation of a normally positioned hemiscrotum which is usually associated with either severe hypospadias or chordee. As regard penoscrotal transposition, a part or the whole scrotum is above the penis. Usually, ectopic scrotum presents as a unilateral hemiscrotum in the suprainguinal region, but it could be detected also inferior to the groin (femoral) or on the thigh but the characteristic sign is the presence of the ipsilateral testis within the ectopic hemiscrotum. On the other hand, in the accessory scrotum, a normally developed scrotum is present but other ectopic scrotal tissues are present either in the perineum or other sites without testis within. In the literature, there are about 30 reported cases either solitary or with other urogenital or non-urogenital abnormalities [6].
Accessory scrotum could be associated with other abnormalities as a perineal lipoma, hypospadias, diphallia, defects of scrotal position, anorectal malformation, and the VACTERL (vertebral, anal, cardiac, tracheoesophageal, renal, and limb anomalies) association [7]. Embryologically, genitalia are hormonally dependent due to the presence of tissue receptors on which dihydrotestosterone works. Subsequently, the penis is developed from the original genital tubercle and both labioscrotal swellings develop into the scrotum at the fourth week of gestation. Both labioscrotal sacs migrate inferomedially to form the scrotum, with a midline scrotal raphe as the fusion line at 12th week of gestation.
The clear explanation for an accessory scrotum is unknown. Embryologically, there are two common theories for the explanation of accessory scrotum. The first one suggests the division of one labioscrotal swelling into two halves with incomplete migration of the inferior portion to   form an accessory scrotum [8]. The second one postulates that the accessory labioscrotal fold usually develops due to an intervening mesenchymal tissue which disrupts the continuity of developing labioscrotal swelling [9]. It is probable that our case presented here is a result of accessory labioscrotal fold. The good indicator here is the absence of other major associated organ anomalies that are usually developed and differentiated at the same antenatal period as neurological and musculoskeletal ones. Our case is considered a rare one not only as an accessory scrotum but due to its pubic position, whereas other positions were illustrated in the perineum and in association with a lipoma [10,11].

Conclusion
The accessory scrotum can be dilemma before a specialist referral. This mandates early discussion in multidisciplinary team including the relevant specialists, beside radiography to determine the precise anatomy, diagnosis, and any associated anomalies. As regard our case, it is unique not only as its pathology but its site also. Data Availability Parents accepted availability of pediatric confidential data on computer system.

Declarations
Ethics Approval and Consent to Participate Informed written consent which was accepted from local Institutional Review Board affiliated to faculty of medicine, Tanta University, obtained from parents for operation in addition to obtaining appropriate institutional ethics committee approval. Local Institutional Review Board approval code: 50922/07/15.

Consent for Publication
Written consent which was accepted from local Institutional Review Board affiliated to faculty of medicine obtained from parents for publication.

Competing Interests
The authors declare no competing interests.
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