Clinical Case 17 - ANSWER

What is your diagnosis for this case ?

A - Intra-oral view demonstrating gingival swelling in the alveolar ridge between canine and premolar teeth.
B - Periapical radiography demonstrating a radiolucent osteolitic lesion with internal osseous septa, and points of calcifications on buccal surface. Besides, shows a thin radiopaque line around the superior aspect of the lesion and resorption of the lamina dura without radicular resorption.

Microscopic view demonstrating a lesion constituted by fibrous connective tissue and abundant nests and strands of inactive-looking OE usually surrounded by basophilic extra-cellular substance (1000×, hematoxilin-eosin).

ANSWER

Central odontogenic fibroma

Case report: A 28-year-old man presented with a painless periodontal swelling in the right side of the mandible. The patient reported five years of evolution, with moderate discomfort during mastication as the only relevant symptom. Oral examination revealed a 2.5 cm sessile tumour on the right side of the alveolar ridge of the mandible, between canine and first premolar (Figure 1.A). These teeth were displaced by the lesion without relevant mobility and positive responses were obtained to thermal test of pulp vitality. The lesion had a firm consistency and was covered by a normal overlying mucosa. There were no clinical signs of inflammation in spite of that surface indentations caused by their upper right canine. On radiographs, it was evidenced a rounded unilocular radiolucent alteration surrounded by a thin radiopaque membrane, with some discrete radiopaque spots. There was not radicular resorption albeit the lamina dura of the affected teeth was not apparent in the proximal aspect to the lesion (Figure 1.B). Puncture of the tumor did not revealed liquid content, and a punch biopsy was performed to obtain a fragment with a myxoid appearance.

Microscopically, the sample consisted in a fibrous connective tissue alternated with more vacuolated myxomatous areas. Individual nuclear morphology of the fibroblasts varied from spindle shaped to stellate. Abundant nests and strands of odontogenic epithelium were found, often with a clear or vacuolated cytoplasm, sometimes surrounded by juxtaepithelial hyalinization (Figure 2). Calcification, inflammatory cells and mitotic activity were not observed. Correlation of clinical, radiographic and histopathological features leaded to the diagnosis of central odontogenic fibroma.

The lesion was then entirely removed by curettage under local anesthesia. The microscopic evaluation of this material reveals the same features of the previous biopsy. All options for rehabilitation were given to the patient, who choice to use a removable partial denture. There was not any relevant event after thirteen years of follow-up.

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