Accessory scrotum in the perineum.

A case of accessory scrotum in a 2-day-old male infant is reported because of its rarity. An overview of sequences during the normal development of male external genitalia has been provided and the deranged mechanism resulting in this anomaly has been reviewed with hypotheses regarding etiology of accessory scrotum.

INTRODUCTION

Congenital scrotal anomalies, rare in incidence, are conventionally classified into four types: bifid scrotum, penoscrotal transposition, ectopic scrotum and accessory scrotum.[1] Accessory scrotum is the occurrence of scrotal skin outside its normal location, either in the perineum or elsewhere, without the presence of testis within it.[23] In a few cases, perineal lipoma has been seen associated with accessory scrotum,[4] and in a few other cases genitourinary abnormalities coexisted.[3] A case of accessory scrotum with proximal femoral focal deficiency has also been reported.[5] At least one case of accessory scrotum has been prenatally diagnosed sonographically during 32 weeks of gestation.[6] It is estimated that there are approximately just over 30 cases of accessory scrotum reported in the literature so far.

An interesting case of accessory scrotum in the perineum with no other associated anomalies is reported with the relevant embryological basis for this condition.

CASE REPORT

A 2-day-old male infant born to a 28-year-old mother presented with an abnormal swelling in the perineum. Examination of the genitalia showed a normal scrotum and penis. The testes were descended and placed within the scrotum. There was another 3 cm × 1.5 cm swelling covered with skin with rugosity suggestive of accessory scrotum. This was situated between the normally sited scrotum and the anal orifice [Figure 1]. No other abnormality was noticed.

Figure 1

Perineum of the case presented. Arrow indicates the accessory scrotum

Four months after the initial consultation, the perineal mass was removed by surgery to restore the normal anatomy. Excision biopsy had the histological appearance of wrinkled skin and subcutaneous connective tissue without fat. The dermal adnexa appeared normal. Sweat glands were absent. These findings were consistent with scrotal skin. The case was reported as “accessory scrotum” and was classified to be of the mid-perineal type. The infant recovered uneventfully.

DISCUSSION

Establishment of normal anatomy of this region is dependent on the interplay of complex events, which are guided by the influence of gonadal steroidal hormone signals.[78] In the case presented here, anomaly was restricted to the presence of an accessory scrotum because of the interference to the normal differentiation of labioscrotal swellings. Review of the literature does not provide information on the confirmed causative mechanism for the occurrence of accessory scrotum.

The anlage of labioscrotal swelling is pleuripotent, and its normal differentiation can be interfered with by the teratogenic agents thereby producing an accessory scrotum. Lamn and Kaplan have suggested that the failure of movement of the labioscrotal swelling to the midline could be responsible for the occurrence of accessory scrotum.[9] Another view by Coupris and Bondonny[10] proposes abnormal division of the labioscrotal swelling as the causative factor for the occurrence of accessory scrotum. Sule, Skoog and Tank have suggested that a developing lipoma in the perineal region could divide the labioscrotal swelling of one side into two or more parts, thereby presenting a case where accessory scrotum is coincident with a lipoma.[4] The probability mentioned last is not relevant in the present case because the accessory scrotum, in this case, is not accompanied by a lipoma. Absence of multiple organ malformations suggests that the causative factor for this anomaly did not have adverse effects on other organ systems getting differentiated simultaneously, like the musculoskeletal system, spine and central nervous system, even though all these structures get differentiated during the same gestational period.

It appears probable that the condition presented here has been a result of abnormal division of the labioscrotal swellings. The interference must have occurred during 9–14 weeks of development, when most of the differentiation of the external genitalia occurs. Absence of other anomalies suggests that the causative factor did not have adverse effects on other organ systems getting differentiated simultaneously, thereby sparing multiple organ malformations.