PMC4247009_01
Clinical examination. Intraoral image revealing a mass with an elastic, hard, well-defined swelling and a smooth surface in the right maxillary molar region. The lesion measured 31x25x15 mm in size.
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The patient complained of painless swelling in the right maxilla that had been present for one month. The facial configuration appeared symmetrical upon clinical examination, but an intraoral examination revealed elastic, hard, well-defined swelling with a smooth surface in the right maxillary molar region. The lesion measured 31x25x15 mm in size (Fig. 1).
Panoramic radiographic finding. Panoramic radiograph revealing the cystic radiolucent lesion in the right maxilla elevating the floor of the right maxillary sinus, indicating the presence of a cystic lesion or odontogenic tumor of the right maxilla.
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Panoramic radiography revealed a cystic radiolucent lesion in the right maxilla elevating the floor of the right maxillary sinus (Fig. 2).
(A and B) Computed tomography (CT) and (C and D) Axial contrast-enhanced magnetic resonance imaging (CE-MRI). (A) Axial CT image revealing a globular-shaped lesion arising from the inside maxillary bone with destruction of its posterior wall and alveolar bone. (B) The lesion exhibited intermediate signal intensity on T1-weighted imaging, and heterogeneous high signal intensity on T2-weighted and short TI inversion-recovery imaging. (C and D) CE-MRI revealed a distinctly-bordered lesion (31x30 mm) extending from the right maxillary alveolar process to the right palate and reaching the retromaxillary fat space.
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These findings indicated that this lesion was a benign tumor, such as an ameloblastoma (Fig. 3A and B). This lesion exhibited intermediate signal intensity on T1-weighted imaging and heterogeneous high signal intensity on T2-weighted and short TI inversion-recovery imaging (Fig. 3C and D).
FDG-PET images. (A) axial and (B) coronal FDG-PET/CT images revealing a slight FDG uptake in the primary tumor of the right maxilla and bilateral superior internal jugular nodes. (C) No abnormal uptake, which would indicate distant metastasis, was observed on FDG-PET images. FDG-PET, 18F-fluorodeoxyglucose-positron emission tomography; CT, computed tomography.
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No abnormal uptake indicating distant metastasis was observed on FDG-PET images (Fig. 4).
Microscopic examination. (A) The majority of the mass consisted of spindle tumor cells exhibiting a storiform, pseudosarcomatous pattern. The epithelial component demonstrated cytological malignancy, characterized by nuclear pleomorphism, an increased nucleus to cytoplasm ratio, hyperchromatic nuclei and a high mitotic rate. (B) In the other area, the tumor cell nest exhibited peripheral palisading of columnar cells, with a vacuolated cytoplasm and reverse-polarized nuclei. These findings resemble those for ameloblastoma. (C) The Ki-67 proliferation index was 5%, indicating that this tumor was of low malignancy.
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The epithelial component demonstrated cytological malignancy, characterized by nuclear pleomorphism, an increased nucleus to cytoplasm ratio, hyperchromatic nuclei and a high mitotic rate (Fig. 5A). These findings were similar to those for ameloblastoma (Fig. 5B). The Ki-67 proliferation index was 5%, indicating that the tumor was of low malignancy (Fig. 5C).
Age and gender. Age and gender distribution revealing the occurrence of maxillary ameloblastic carcinoma in different age groups and genders.
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A breakdown of the age distribution is presented in Fig. 6.
Kaplan-Meier curves for (A) disease-free survival (DFS) and (B) overall survival (OS). The five-year and 10-year DFS rates were 53.7 and 32.2%, respectively. The five-year OS rate was 83.2% and the 10-year rate was 32.2%, the same as the DFS rate.
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Kaplan-Meier survival curves for disease-free survival (DFS) and overall survival (OS) are presented in Fig. 7A and B, respectively.