Prenatally diagnosed accessory scrotum: A case report and review of the literature on prenatal features.

Accessory scrotum (AS) is rarely diagnosed antenatally, and its prenatal features remain unknown. Here, we report a case of a prenatally diagnosed accessory scrotum with perineal lipoma. A 33-year-old woman was referred to our hospital at 35 weeks of gestation to evaluate a mass in the fetal perineal region. Prenatal ultrasonography showed a 2.0 × 2.0 cm sized, echogenic, and circular mass located posterior to the left scrotum in a male fetus. Magnetic resonance imaging (MRI) showed a mass containing adipose tissue. A 6.5 cm elastic mass (AS and protruding lipoma) was observed in the perineal region, and surgical excision was performed at 8 months of age. Histological examination confirmed the diagnosis of AS with perineal lipoma, and there was no recurrence at follow-up. The typical prenatal presentation of AS was a circular perineal mass located posterior to the normal scrotum and was associated with perineal lipoma. The prenatal detection of AS was feasible with careful observation via ultrasonography, and prenatal MRI was useful in characterizing perineal tumors and evaluating associated anomalies.