Severe microhydranencephaly: differential diagnosis with anencephaly Barth MB, Silveira DB, Pelizzari E, Da Rosa EB, Tsugami LSG, Bellé NL, Cunha AC, Betat RS, Zen PRG, Rosa RFM Hospital Materno Infantil Presidente Vargas, Porto Alegre, Brazil
Objective To report the prenatal findings of a fetus with microhydranencephaly, initially referred with suspected diagnosis of anencephaly. Methods To report a rare condition of microhydranencephaly and to present the literature review. Results We report about 32 years old primigravida. She was referred to the Fetal Medicine due to suspicion of anencephaly, firstly diagnosed at 21 weeks gestation. Primary the cranial vault could not be clearly visualized. Morphological ultrasound performed at our hospital at 24 weeks gestation identified the fetal skull with significant microcephaly. Brain structures were not well defined, however interhemispheric division was observed. In subsequent examination performed 4 weeks later, there was also polyhydramnios (AFI was 23. 4). Fetal magnetic resonance imaging revealed severe atrophy of the cerebral hemispheres, thalamus, midbrain, cerebellum and brainstem; there were signs of diffuse spinal cord atrophy and microcephaly. There was fluid accumulation greater than that normally identified in the nasopharynx and oropharynx, being interpreted as a possible association with a swallowing disorder. The findings were indicative of a diagnosis of microhydranencephaly. Fetal echocardiography, TORCH serology and karyotype (46, XY) were normal. The pregnancy progressed with marked polyhydramnios, requiring drainage of amniotic fluid. The fetus was born prematurely soon after the amniodrainage and died soon after birth. Conclusion The diagnosis of skull defects such as anencephaly, can be established by ultrasound in the first trimester of pregnancy, after the period of mineralization. It is important to note that cases of severe microhydranencephaly, as observed in our case, can mimic the findings of anencephaly, which is considered as possible differential diagnosis. This may have important implications for genetic counseling due to different etiologies and different legal issues related to a pregnancy termination in Brazil.