Hidden Hollows of the Fetal Cranium-Lacunar Skull in Isolation.

Introduction: Lacunar skull, also known as Lückenschädel or craniolacunae, is a rare congenital calvarial ossification abnormality characterized by multiple lucent defects of the skull. It is most associated with neural tube defects, Chiari II malformation, craniosynostosis, and other congenital anomalies. Isolated lacunar skull, without associated structural abnormalities, has been infrequently reported, and its natural history, prognosis, and optimal clinical management are poorly defined. Case Presentation: We report the case of a female infant born at 38 weeks and 5 days' gestation to a 37-year-old gravida 6 para 3033 mother following an uncomplicated pregnancy. Prenatal genetic screening and serial fetal ultrasonography demonstrated no fetal anomalies, although a bilobed heterogeneous placenta was noted. Following an uncomplicated spontaneous vaginal delivery with Apgar scores of 8 and 9, a boggy right parietal scalp abnormality was identified on routine neonatal examination. Initial skull radiographs were inconclusive. Computed tomography (CT) with 3D reconstruction demonstrated multiple asymmetric lucent calvarial defects, more pronounced within the right parietal and occipital bones, consistent with lacunar skull. Brain parenchyma, ventricles, cranial sutures, and spine were normal. Additional evaluations revealed no associated abnormalities. Diagnostic genetic testing was deferred as no syndromic features or additional congenital anomalies were identified on evaluation. Conservative management with close clinical observation was recommended. At 6 weeks of age, the infant demonstrated normal neurological examination and age-appropriate developmental progress. Discussion: This case describes an uncommon presentation of isolated lacunar skull diagnosed postnatally in an otherwise healthy term infant with normal prenatal imaging. Unlike most reported cases, no associated central nervous system, skeletal, or syndromic abnormalities were identified following comprehensive evaluation. This report highlights the importance of distinguishing isolated lacunar skull from more common associated conditions, outlines an appropriate diagnostic evaluation, and supports conservative management with ongoing developmental surveillance in the absence of additional abnormalities.