Prenatal ultrasound diagnosis of harlequin ichthyosis: A rare congenital skin disorder

Introduction: Harlequin ichthyosis is a rare and severe congenital skin disorder of autosomal recessive origin. Ichthyosis represents a group of inherited disorders characterised by abnormal keratinisation and skin barrier dysfunction. Sonographers, fetal medicine specialists and radiologists need to be aware of this condition as it presents as an evolving fetal anomaly. Case presentation: We report a 27-year-old pregnant female who presented for a routine antenatal scan at 29 weeks. The ultrasound examination revealed a single live fetus with thick skin, abnormal facial features and amniotic fluid containing internal echoes. Based on these ultrasound features, the condition was diagnosed as harlequin ichthyosis. After genetic counselling, the couple opted to discontinue the pregnancy and underwent medical termination of pregnancy. The morphology of the phenotype confirmed the ultrasound imaging findings. Discussion: Harlequin ichthyosis is a rare and severe congenital ichthyosis of autosomal recessive origin. The condition is characterised by plate-like scales covering the entire body, typical facial features such as ectropion, eclabium, flat nose, fixed flexion deformities of the extremities and amniotic fluid with internal echoes. Ultrasound is the optimal first-line imaging modality for assessment of these features. The combined use of two-dimensional and three-dimensional ultrasound imaging aids in better depiction of the facial morphology. Detailed genetic evaluation is recommended to assess gene mutations and predict recurrence risk in subsequent pregnancies. Conclusion: While harlequin ichthyosis is rare, recognising the sonographic features early can help in genetic counselling and guide management, empowering obstetricians.