Abstract: The middle interhemispheric variant of holoprosencephaly (MIH) is a variant type of holoprosencephaly. In this article, we report the case of a 15-year-old male patient with MIH who presented with a forehead bulge immediately after birth. He was admitted to the hospital for surgery due to a frontal lesion affecting his appearance. CT and MRI revealed a frontal bone lesion and incidentally detected MIH associated with bilateral frontal lobe polymicrogyria. Postoperative pathology of the median frontal bone lesion confirmed it to be an osteoma. This article retrospectively analyzes the CT and MRI imaging features of MIH with frontal midline osteoma and reviews the literature to summarize the imaging characteristics of MIH, aiming to improve the understanding of this rare disease.