Segmental odontomaxillary dysplasia (SOD) is a rare developmental disorder of the maxilla, and there is little information on its morphological features. Thus, the present article describes a case of SOD focusing on its histopathological, immunohistochemical and scanning electron microscopic features. Several dental abnormalities were present, including numerous dentin and pulp defects, altered composition of hard tissue, and proliferation of myofibroblasts in the pulp and the soft tissue surrounding affected teeth. This myofibroblastic proliferation was identified for the first time in SOD and may be involved in both bone and tooth resorption mechanisms.