Metastasizing ameloblastoma

@#A 27-year-old man presented with an 8 cm diameter left maxillary mass and an enlarged cervical lymph node at levels II to III. There was a reported history of a previous unspecified operation on the maxillary mass which had yielded a diagnosis of ameloblastoma. Total maxillectomy with modified radical neck dissection was subsequently performed. Microscopic examination of the maxillary mass shows epithelial islands and cords in a fibro-collagenous stroma. (Figure 1) The islands and cords are lined in the periphery by palisaded columnar cells with regular ovoid nuclei exhibiting reverse polarization. The nuclei are uniform with dispersed chromatin and no significant atypia. Towards the center of these islands are loosely arranged spindly to stellate cells (“stellate reticulum”). (Figure 2) Microscopic examination of the largest submitted lymph node shows an epithelial neoplasm with identical histologic features as the maxillary mass and a residual rim of lymphoid tissue at the periphery enclosed by the nodal capsule. (Figure 3) Similarly, there is neither atypia nor pleomorphism and only a few typical mitotic figures are seen in the nodal tumor. (Figure 4) These features support the diagnosis of a metastasizing ameloblastoma (MA).

Calcifying cystic odontogenic tumor associated with a complex odontoma

@#We present a case of a 16-year-old lad with a one year history of gingival mass of the left maxillary alveolar ridge. Excision revealed a cystic mass with brown fluid and irregular calcified material within the cavity. Histopathologic examination of the cyst lining shows a stratified cuboidal epithelium with palisading of the basal layer. The cells of the latter show reverse nuclear polarization reminiscent of ameloblastic epithelium. The superficial layers have a stellate reticulum-like appearance and contain large eosinophilic polygonal ghost cells. (Figure 1, 2) Some of the ghost cells show calcifications. (Figure 3) Sections from the hard, bony fragments show haphazard deposition of dentin and enamel-like material. (Figure 4) With these features, this case was called a calcifying cystic odontogenic tumour in association with a complex odontoma. Calcifying cystic odontogenic tumor (CCOT) is a benign neoplasm characterized by an ameloblastoma-like epithelium with ghost cells that often show calcification.1 It comprises only 2% of all benign odontogenic neoplasms.2 There is equal distribution of involvement for the maxilla and mandible, no sex predilection, with most cases diagnosed at the 2nd to 3rd decade of life.1,2 The classic histologic findings are the presence of a stratified epithelium consisting of cuboidal to columnar cells with reverse polarization of the basal layer and the presence of ghost cells. A stellate reticulum-like appearance of epithelial cells is also seen. Ghost cells are the most characteristic feature of CCOT and this may represent an abnormal type of keratinization or the coagulative necrosis of the odontogenic epithelium.