A Large Arachnoid Cyst in a Preterm Infant: A Case Report and Management Insights

Although arachnoid cysts, particularly large cysts in the posterior fossa, are rare in preterm infants, early diagnosis using advanced imaging techniques is essential. We describe the case of a preterm infant born at 30 + 6 weeks gestation, presenting with respiratory distress and requiring resuscitation. Prenatal ultrasonography revealed lateral ventricular dilation and a posterior fossa cyst. Postnatal cranial ultrasonography and magnetic resonance imaging confirmed the presence of a large arachnoid cyst, which was conservatively managed. This case highlights the utility of prenatal/postnatal imaging for identifying arachnoid cysts and the importance of early diagnosis and management. Conservative management is effective in asymptomatic patients.