[CT diagnosis of various subtypes of ameloblastoma in the maxillomandibular region]

Abstract

Background & objective: Based on biological behavior and histopathologic characteristics, ameloblastomas in the maxillomandibular region can be divided into several subtypes with different prognosis. This study was to explore the clinical and CT imaging features of solid or multicystic ameloblastoma (SMA), unicystic ameloblastoma (UA), and malignant ameloblastoma (MA), and thus to improve the CT diagnostic accuracy for these diseases.

Methods: Clinical and CT features of 25 histologically proven ameloblastomas in the maxillomandibular region, including 14 SMAs, 6 UAs, and 5 MAs were analyzed retrospectively.

Results: The median age of the patients initially diagnosed as SMA, UA, and MA were 33.5, 20.5, and 56 years, respectively. The mean maximal transverse diameters on CT images were 33 mm for SMA, 46 mm for UA, and 59 mm for MA. Of the 14 SMAs, 11 (79%) showed low to intermediate density as compared with muscles, 3 (21%) showed homogenous and intermediate density; 12 (86%) appeared as lobulate lesions; 10 (71%) had incomplete bone septa; 9 (64%) showed root resorption of the neighboring teeth; 13 (93%) showed cortical perforation; 6 (43%) had soft tissue masses; all SMAs showed well-defined margins. Of the 11 SMAs examined by enhanced studies, 9 (82%) showed strong enhancement. CT images of the 6 UAs showed homogenous and low density in comparison with muscles. Of the 6 UAs, 2 (33%) were lobulate, 4 (67%) were regularly round or oval; 1 (17%) had bone septa, 2 (33%) had root resorption of the neighboring teeth, 3 (50%) had cortical perforation. All UAs showed well-circumscribed margins without soft tissue masses. Three UAs were examined by enhanced studies and showed mild to moderate enhancement of the wall. Of the 5 MAs, 3 (60%) showed low to intermediate density as compared with muscles, 2 (40%) showed homogenous and intermediate density; 3 (60%) had bone septa; 3 (60%) showed root resorption or destruction of the neighboring teeth. All 5 MAs were lobulate with cortical perforation, soft tissue masses, and ill-defined margins. All 3 MAs examined by enhanced studies showed strong enhancement.

Conclusions: SMAs are usually seen in middle-aged patients. CT images of SMAs frequently show lobulate lesions with strongly enhanced solid and cystic components. UA occurs mostly in young patients, and typically appears as cystic lesion with mild to moderate enhancement of the wall on CT images. MA often appears in old patients, and shows extensive bone destruction, soft tissue mass, ill-defined margin, and strong enhancement on CT images. Combined analysis of CT images and clinical data is helpful in differentiating these 3 subtypes of ameloblastoma.