Conclusions: The most likely cause of lesions with an absence of the long process of the incus was congenital origin because many cases were associated with the stapedial anomaly. However, the possibility of a potential inflammation of this lesion could not be completely excluded, especially in cases with only an absence of the long process of the incus.
Objective: To clarify whether the absence of the long process of the incus is caused by congenital anomaly or a potential inflammation.
Subjects and methods: A total of 21 patients (5 bilateral cases, 16 unilateral cases) with absence of the long process of the incus were reviewed. Operative and histopathological findings of the removed incus were analyzed.
Results: The 21 cases with absence of the long process of the incus were classified into 6 types. Thirteen cases showed the absence of the long process associated with the stapedial anomaly, which were all unilateral. Eight cases showed no association with the stapedial anomaly, among which five cases were bilateral. Three of eight cases not associated with the stapedial anomaly showed evidence of resorption in the incus body such as fibrosis and Haversian canal widening.