Unicystic ameloblastoma metastasizing to multiple cervical lymph nodes
In 2009, a 26-year-old Japanese female patient was referred to our clinic, presenting with radiolucent cystic lesion in the left mandibular region. On oral examination, no swelling appeared to gingiva of the lower left second molar region. Neither paresthesia of the mental region nor palpable lymphadenopathy was observed. Panoramic radiography showed a radiolucent cystic lesion measuring 15 mm in diameter with impacted wisdom tooth (Fig. A). CT revealed a cystic lesion surrounding the crown of the wisdom tooth (Fig. B). Under clinical diagnosis of a dentigerous cyst, enucleation of the cystic lesion and removal of the wisdom tooth were performed (Fig. C). Histopathogical diagnosis was unicystic ameloblastoma (Fig. A and B). The postoperative course was uneventful.\nIn May 2012, this patient complained of a swelling at the left submandibular region of 2 months' duration (Fig. A). Physical examination showed a soft, mobile mass 30 mm in diameter in the submandibular area, and there was no clinical and radiographic sign of recurrence in the left mandibular lesion in the follow-up period (Fig. B). A CT scan with contrast medium showed a bilobed mass-like mucocele compressing the submandibular gland (Fig. C). MRI revealed that the contents of this mass were fluidic. A chest X-ray showed no abnormal finding. The patient underwent extirpation of a cystic mass with the submandibular gland and the associated lymph nodes (Fig. D). The submandibular mass showed a smooth surface covered with this capsule, and its contents was yellowish, transparent, mucinous liquid. The final histopathological diagnosis was consistent with ameloblastoma encapsulated in the mass and encapsulated with two metastatic lymph nodes. The patient had an uneventful postoperative course. In July 2012, the patient received CT scan of the mandible, neck and chest, and all regions were disease-free. The patient was placed on a strict follow-up schedule, with annual CT and chest X-ray. At the follow-up, the patient maintained disease-free.\nMacro- and microscopically, the primary lesion was a typical cystic lesion including an unerupted wisdom tooth. Cyst wall consisted of ameloblastomatous epithelium which was laminated by palisading and nuclear polarized cells without any mitotic features (Fig. A and B). The lesion was diagnosed as a unicystic ameloblastoma, intraluminal type. The submandibular mass was cystic and lymph follicles were seen in the cyst-like wall (Fig. D). The laminated epithelium of cyst wall was ameloblastomatous epithelium similar to that of primary tumor, and presented no atypia and mitotic figures (Fig. E). The ameloblastomatous tumors also were found in the cervical lymph nodes. Cell proliferative analysis of submandibular lesion by Ki-67 immunohistochemical staining, however, indicated obviously high index compared with primary lesion, and the index ratio is <5% in primary lesion but >10% in palisading and nuclear polarized cells of metastatic lesion (Fig. C and F). Therefore, final diagnosis of tumor was metastasizing unicystic ameloblastoma.