Maxillary calcifying epithelial odontogenic tumor with sinus and buccal vestibule extension: a case report and immunohistochemical study

A 45 year old female presented to our institution with a diffuse swelling of the left maxilla which caused a mild tumefaction of the left cheek and obliteration of the buccal vestibule, left cheek pain during chewing with auricular and temporal irradiation, and masticatory disorders. The patient reported the onset of symptoms about 3 weeks before, but the exact duration of the swelling is not known. However, the patient remembered that about 3 years ago she was complaining of pain in the molar region of left maxilla and she addressed to her dentist. Without X-ray examination it was decided for extraction of the 2nd molar which presented palatal ectopia, but without caries and no abnormal mobility. Personal or family records were not significant, but noteworthy is that she worked about 10 years as an industrial dyer.

Extraoral examination revealed a mild diffuse swelling of the left cheek, most obvious at the posterior side of the zygomatic region. It was painless and hard in consistency on palpation. Intraoral examination revealed a diffuse swelling extending from the maxillary left first premolar to the tuberosity and retromolar regions that obliterated the buccal vestibule (Fig. 1a). The overlying mucosa was stretched but intact. On palpation, at the level of maxillary alveolar process the swelling was hard and painless but became fluctuating and slightly tender in the retromolar region.

Orthopantomogram showed a radiolucent lesion involving the left maxillary tuberosity, alveolar process, and the maxillary sinus with erosion of lateral wall and floor of the sinus (Fig. 1b). On computed tomography scan it was noticed an expansile, radiolucent lesion of the left maxilla (about 4 cm in diameter) with scattered areas of calcification which completely obliterated the left maxillary sinus (Fig. 1c). The scan showed tumor extension and involvement of the alveolar process (behind the first premolar with buccal cortical thinning, erosion and invasion of the soft tissue from retromolar region), maxillary sinus (with erosion of lateral and nasal walls, and floor of the sinus) and palatine process.

Based on history, clinical and imaging findings, a provisional diagnosis of benign locally aggressive odontogenic neoplasm of the left maxilla was considered. Under general anesthesia, a subtotal maxillectomy procedure was performed through Dieffenbach’s modification of Weber–Fergusons incision followed by defect reconstruction.

The surgical specimen included almost the entire left maxilla, respectively the entire zygomatic process, the distal alveolar process with corresponding teeth, and limited area of the frontal and palatal processes, measuring 4.5 × 4 × 3 cm in total (Fig. 1d). The tumor eroded the floor and anterolateral wall of the maxillary sinus, occupying the entire left maxillary sinus being adherent to the lining mucosa but without its ulceration. Also, this tumor distorted the left alveolar process starting from the second bicuspid tooth up to the retromolar area, destroying the left maxillary tuberosity and distal to the third molar tooth becoming adherent to the vestibular mucosa but without its ulceration. The palatal process was partially involved but without palatal fibromucosa invasion. The tumor itself was relatively well defined, with smooth surface and firm in consistency. On cut section it appeared as solid, whitish gray with various amounts of calcification, and with sandy-like consistency.

The tumor was composed of variable amounts of polyhedral eosinophilic epithelial cell islands, cords and strands in a fibrous stroma. These neoplastic cells had well-defined boundaries, intercellular bridges in focal areas and some degree of nuclear pleomorphism, including few bizarre nuclei (Fig. 2a). Between cells and within tumoral stroma, there was a conspicuous homogeneous eosinophilic acellular material that stained positive for Congo red (Fig. 2b). This material was confirmed as amyloid by examination in polarized light after Congo red staining, with the deposits exhibiting the characteristically apple-green birefringence (Fig. 2c). Some of the small round-shaped amyloid-like entities undergone calcification and only a few of them presented Liesegang rings. We also noticed the presence of areas with accentuated nuclear pleomorphism (Fig. 2d), some multinucleated giant cells (Fig. 2e), scattered S100 positive clear cells (Fig. 2f), and few clear cells with intracytoplasmic PAS-positive granules (glycogen). Altogether, the tumor did not raise the suspicion of another origin, as for example a primary or metastatic intraosseous squamous cell carcinoma. In some areas, between neoplastic proliferations were also observed small rounded cementum-like deposits (Fig. 2g). The tumor proliferations penetrated the cortical plates of maxillary bone invading the connective tissue of the maxillary sinus mucosa and the vestibular mucosa but without involvement of the lining epithelium (Fig. 2h, i).

The polyhedral neoplastic epithelial cells were diffusely cytoplasmic immunoreactive for CK 5/6 and CK19, while the clear cells were negative for these epithelial markers, exhibiting a nuclear and cytoplasmic positivity for the anti-S100 protein. Also the tumor polyhedral cells had an intense nuclear reactivity for p63, and with the cytoplasm slightly positive for vimentin, but negative for α-smooth muscle actin.

In order to explain its extremely aggressive behavior we investigated tumor cell immunoreactivity for a number of markers related to tumor invasiveness, as listed in Table 1. Thus, we observed expression of matrix metalloproteinases (MMP)-1, MMP-2, MMP-3, and MMP-9 mainly in the nuclei of tumor cells, while for MMP-3 and MMP-9 the immunoreactivity was also present in the cytoplasm of tumor cells and in the amyloid deposits (Fig. 3a, b). In addition, collagen IV reactivity was detected as a linear pattern around the tumor islands, sheets and nests but with variable thickness along the tumor tissue with discontinuities at the advancing edge (Fig. 3c).

Investigation of markers involved in cell adhesion showed a positive reaction with prevailing membranous pattern in the tumor cells for E-, N- and P-cadherin, Integrin β1 and Beta-catenin. However, as a peculiarity of the tumor advancing edge, where small groups or cords of infiltrating tumor cells were present, the staining pattern became also cytoplasmic for all cadherins, Integrin β1 and Beta-catenin (Fig. 3d), and even nuclear for N- (Fig. 3e) and P-cadherin. In these areas the membranous immunoreactivity decreased and at least for E-cadherin we noticed an increased cytoplasmic colocalization with vimentin (Fig. 3f).

Investigation of other markers involved in the epithelial-mesenchymal transition process revealed mostly a nuclear reactivity of tumor cells for Twist 1 and Slug 1 (Fig. 3g) that seemed to be more intense at the advancing edge. Also, the chemokine receptor −4 (CXCR4) reactivity was also noticed in tumor cells with membranous, cytoplasmic and even nuclear pattern (Fig. 3h) Moreover, the podoplanin tumor cell reactivity, with a membranous pattern, was more obvious at the advancing edge, at the periphery of tumor proliferations (Fig. 3i). However the Ki-67 labeling index in tumor cells was less than 3% and without any significant difference regarding the tumor topography.

A final diagnosis of intraosseous CEOT with maxillary sinus and buccal vestibule submucosa extension was made on the basis of the above findings. After 12 months of follow-up, the patient did not present any clinical or radiographic evidences of recurrence.