Case report

This was the first pregnancy of a nonconsanguineous couple. The first sonography screening at 13 weeks and triple test at 16 weeks were normal. At 24 weeks a spina bifida or a "subtle skin-covered spinal dysraphism" was suspected, without cerebral ventriculomegaly. The patient was referred to our unit at 27 weeks and our observation found:

• A hypoechoic lesion (10x60 mm) at the level of the right buttock with an apparently normal bony structure of the spine;
• Moderate bilateral ventriculomegaly with absence of dilatation of the third ventricle were seen;
• Normal corpus callosum and architecture of the pericallosal artery;
• Normal posterior fossa;
• Normal fetal movements and normal anatomy of the rest of the fetus.

Our presumed diagnosis was pilonidal cyst.

At 33 weeks the finding was confirmed. No cerebral lesion was found and the width of the lateral ventricles was 5 mm. An MRI was done at 33 weeks and no sings of meningocele were present. An amniocentesis revealed normal karyotype. The acetyl-cholinesterase level as well as the serological tests (Toxoplasmosis, Rubeola, CMV, Herpes, Chikungunya) were normal too.

The neonate was born at 38 weeks. The diagnosis of the isolated pilonidal cyst was confirmed. The surgical treatment was not done yet.

Images 1, 2: 27 weeks of pregnancy; Oblique coronal scans showing a mostly hypoechoic subcutaneous lesion in the lumbar region of the fetus.

Images 3, 4: 27 weeks of pregnancy; Sagittal scans showing a mostly hypoechoic subcutaneous lesion in the lumbar region of the fetus.

Images 5, 6: 27 weeks of pregnancy; Oblique coronal scans showing a mostly hypoechoic subcutaneous lesion in the lumbar region of the fetus.

Image 7: 27 weeks of pregnancy; Transverse scan showing a hypoechoic subcutaneous lesion in the lumbar region of the fetus.

Images 8, 9: 27 weeks of pregnancy; 3D images showing a subcutaneous lesion in the lumbar region of the fetus.

Images 10, 11: 27 weeks of pregnancy; Image 10 shows a slight cerebral ventriculomegaly. Image 11 shows normal corpus callosum of the fetus.

Images 12, 13: 27 weeks of pregnancy; Images show normal pericallosal artery of the fetus.

Images 14, 15: 33 weeks of pregnancy; Sagittal scans showing a mostly hypoechoic subcutaneous lesion in the lumbar region of the fetus.

Images 16, 17: 33 weeks of pregnancy; Coronal (Image 16) and transverse images (Image 17) showing a mostly hypoechoic subcutaneous lesion in the lumbar region of the fetus.

Images 18, 19: 33 weeks of pregnancy; MRI images showing a subcutaneous lesion in the lumbar region of the fetus.

Images 20, 21: Postnatal appearance of the baby.