Fetal hepatic hamartoma and placental mesenchymal dysplasia

Ziel: Fetal hamartoma constitute a rare benign lesion of the mesenchymal tissue. We herein describe the antenatal diagnosis and management of a giant hepatic mesenchymal hamartoma in conjunction with a placental mesenchymal dysplasia (PMD).

Methodik: A 29-year old II gravida I para, was referred at 13+3 weeks due to an abnormal placenta. The initial ultrasound (US) findings were suspicious of a partial hydatidiform placenta. At 20 weeks, targeted US firstly revealed an infradiaphragmatic cystic mass (19×17×19mm). Due to the rapid growth, its avascular nature and location of the lesion, a hamartoma has been assumed. At 27+4 weeks inpatient admission was necessary because of preterm labour, prompting an immediate c-section (pre-operative measure 98×73×86mm). A female premature infant was delivered weighing 1,452g, with Apgar scores of 5 and 8 at 5 and 10 minutes. Repeated abdominal punctures of the cystic lesion were performed, the mass subsequently resolved leaving an echogenic area in the left hepatic lobe.

Ergebnis: Histopathological findings and immunohistochemistry were rather consistent with a placental mesenchymal dysplasia (PMD) than a hydatidiform placenta. The main characteristic finding is the absence of abnormal trophoblast proliferation. This placental anomaly is potentially associated with an adverse pregnancy outcome, (incl. IUGR, fetal demise, neonatal death) depending on the relative size and growth of the remaining functional placenta. It is suggested that continuous inadequate blood supply may cause aneurysmal dilation of the chorionic vessels and hyperplasia of placental stem villi. Secondarily, ischemic lesions of the fetal liver occur, finally resulting in large progredient cystic masses.

Schlussfolgerung: The extreme paucity of antenatal data and the frequent underdiagnosis of PMD underline the diagnostic dilemma. Detailed anatomic survey and serial US exams are madatory to detect fetal compromise and associated anomalies.

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