Prenatally detected congenital perineal mass using 3D ultrasound which was diagnosed as lipoblastoma combined with anorectal malformation: case report

Abstract

We report a case of prenatally diagnosed congenital perineal mass which was combined with anorectal malformation. The mass was successfully treated with posterior sagittal anorectoplasty postnatally. On ultrasound examination at a gestational age of 23 weeks the fetal perineal mass were found on the right side. Any other defects were not visible on ultrasonography during whole gestation. Amniocentesis was performed to evaluate the fetal karyotyping and acetylcholinesterase which were also normal. As the fetus grew up, the mass size was slowly increased more and more. At birth, a female neonate had a perineal mass on the right side as expected. During operation, the anal sphincteric displacement was found near the mass and reconstructed through posterior sagittal incision. This is the first reported case of prenatally diagnosed congenital perineal mass, after birth which was diagnosed as lipoblastoma and even combined with anorectal malformation. This case shows that it can be of clinical importance to be aware of this rare fetal perineal mass in prenatal diagnosis and counseling.

Keywords: Anal Canal; Congenital Abnormalities; Lipoblastoma; Perineum; Prenatal Diagnosis.

Fig. 1

(A) 2D and (B) 3D ultrasonographic findings of fetal perineal mass (arrow) with hypoechoic shadow at 36 weeks' gestation.

Fig. 2

At birth, pedunculated round soft mass, measuring 3×2.1×2 cm, was visible on the right posterior labium major of the newborn.

Fig. 3

The mass was excised completely under general anesthesia. The skin shows no remarkable finding. On section, the cut surface shows soft adipose tissue-like material.

Fig. 4

The tumor was composed of irregular small lobules of immature fat cells separated by connective tissue septa of varying thickness and mesenchymal areas with a loose myxoid appearance. Hematoxylin and eosin stain, (A) 40× and (B) 100× magnifications.