Prenatal diagnosis and postnatal follow-up of pericallosal lipoma: report of seven new cases

Abstract

Background and purpose: Pericallosal lipomas are rare tumors. Few reports have included their imaging characteristics. Furthermore, little is known about their evolutive course. Our purpose was to describe the imaging features of seven cases of pericallosal lipoma diagnosed in utero and followed up after birth.

Methods: We reviewed seven cases of pericallosal lipoma diagnosed by obstetric sonography (n = 7) and examined by fetal MR imaging (n = 5). Analysis of the complementary findings provided by fetal MR imaging was conducted. All findings were correlated with the postnatal imaging and clinical findings.

Results: Obstetric sonography easily showed the pericallosal lipoma in all seven patients. In one, however, it was misinterpreted as intracranial hemorrhage. The morphology and integrity of the underlying corpus callosum were less easy to assess by using sonography. Fetal MR imaging confirmed the fatty content and location of the lesion in all five cases. It showed the choroidal extension in two patients and the type of associated callosal anomaly in another patient better than did sonography. In two patients, the lipoma grew, as revealed by subsequent postnatal MR imaging. The results of the neurologic examinations remained normal for the five surviving patients at a mean follow-up of 3 years (1 month-9 years).

Conclusion: Obstetric sonography is able to easily show pericallosal lipoma. Fetal MR imaging may be useful to characterize the lipomatous nature and the extension of the lipoma and the status of the corpus callosum. Long-term follow-up is necessary to understand the clinical consequences of such lesions.

fig 1.

Tubulo-nodular type of pericallosal lipoma. In utero and postnatal follow-up images (case 3). A, Sonogram obtained in utero at 35 weeks' gestation. A biparietal image is shown. A hyperechoic mass (M) can be seen within the anterior midline. The lipoma appears slightly less echogenic than the parietal bone; its margins are irregular. The mass is extending toward the frontal lobes (arrows). B, MR image obtained at birth. Sagittal view turbo spin-echo T1-weighted image (350/16/1) confirms the presence of the lipoma and the agenesis of the corpus callosum. C, MR image obtained at birth. Frontal view turbo spin-echo T1-weighted image (350/16/1) shows the lateral extend of the lipoma. D, MR image obtained at age 3 years. Mid-sagittal view turbo spin-echo T1-weighted sequence (450/15/1) shows the growth of the lipoma. E, MR image obtained at age 3 years. Similar findings are revealed by the frontal view turbo spin-echo T1-weighted sequence (450/15/1).

fig 2.

Tubulo-nodular type. Fetal MR images (case 4). A, Mid-sagittal view turbo spin-echo T1-weighted sequence (400/17/1) shows typical lipoma and incomplete corpus callosum. Note that it was not possible to obtain this sagittal view image by using obstetric sonography. B, Transverse turbo spin-echo T1-weighted sequence (400/17/1) shows the lipoma and the extension toward the plexus choroids.

fig 3.

Curvilinear pattern. Sonograms and fetal MR images (case 7). A, Obstetric sonograms obtained 26.5 weeks. Sagittal view image of the fetal head. The lipoma appears as a hyperechoic mass (arrowheads) with smooth margins parallel to the corpus callosum (arrow). B, Fetal MR image. Mid-sagittal fast spin-echo T2-weighted sequence (8000/122/2) shows a curvilinear hyposignal lipoma and a normal corpus callosum.