Duplicated, Translocated Upper Lip and Maxilla: An Extremely Rare Congenital Craniofacial Anomaly With Novel Genetic Findings.

IMPORTANCE: Diprosopus is an exceedingly rare craniomaxillofacial dysmorphosis that is considered a subgroup of conjoined twins. This phenotype encompasses a broad spectrum of duplications ranging from partial structures to complete dicephalus. The embryogenesis and mechanism of disease are not well understood. The objective of this investigation was to describe a case of partial dentofacial duplication and to discuss the possible etiology with novel genetic insights thereof.

OBSERVATIONS: A newborn Kazakh boy was referred to the First Affiliated Hospital of Xinjiang Medical University because of a maxillary mass detected on prenatal imaging. Physical examination revealed a unilateral cleft lip and a soft lump around 2.5 cm in diameter with the appearance of an accessory upper lip. He underwent two surgical procedures at 11 months and 4 years of age for definitive treatment. He demonstrated favorable recovery outcomes, maintaining normal speech and oral intake capabilities during long-term follow-up.

CONCLUSIONS AND RELEVANCE: Our preliminary findings and comprehensive literature review suggest that mutations in the PAX7 gene could contribute to the pathogenesis of craniofacial duplication. This hypothesis establishes a previously unrecognized association between specific genetic alterations and the clinical manifestations of this condition, potentially offering a molecular foundation for prenatal diagnostic approaches. The present case provides more profound insights into the disease mechanisms compared to prior reports. Further validation through basic scientific investigations and clinical studies, incorporating comprehensive genetic analyses, will be essential to substantiate this proposed mechanism.