A Case of Developmental Anomaly of the Process of Folius Associated with Conductive Hearing Loss / 대한이비인후과학회지

ABSTRACT

The anterior process of the malleus (process of Folius) in the middle ear develops through an intramembranous ossification center that appears in the human embryo of 26.5 mm crown-rump length at a caudomedial position in relation to Meckel's cartilage. We present one case of an ossicular anomaly considered to consist of an abnormality of the anterior process and manubrium mallei (malleus handle). In this case, a thick bony bar was found extending from the neck of the malleus and abnormally developed an anterior process of the malleus to the posterior bony wall or the tympanic bone. In the anterior part, a thick bony bar was also found in the anterior bony wall connecting with the malleus neck and the anterior process of malleus, which was abnormally developed by fibrous tissue. The manubrium mallei and the umbo were not identified and the anterior process of the malleus was recognized as an abnormally developed bony fragment. On the basis of these findings, the bony bar was assumed to represent an abnormally developed mesenchyme bone (os goniale), which later developed into the anterior process of the malleus.