Diagnostic Information

History of Present Illness

The patient had a presumed acute inflammatory episode associated with the mandibular left third molar (tooth #17). He had mild pain and swelling in the area and was treated by extraction of the tooth. During the next six months he continued to experience progressive enlargement and pain at the extraction site. An attempt to incise and drain the area was performed, but no purulence could be obtained. Subsequently, the patient was referred to an oral and maxillofacial surgeon for evaluation and management.

Past Medical History

His medical history included nasal surgery (unspecified condition), depression, and recent involuntary weight loss. The patient smoked one pack of cigarettes per day (15 year-pack history), consumed at least two alcoholic beverages per day, used smokeless tobacco, and used crack cocaine.

Clinical Examination Findings

The patient exhibited left facial swelling (Figures 1, 2). Intraoral examination revealed a firm mass involving the left posterior mandibular region (Figures 3, 4). The lesion occupied the retromolar pad, buccal vestibule, and mandibular ridge. Lingual alveolar expansion was also palpable in the floor of the mouth. The surface of the lesion appeared lobulated with a purple/gray coloration, and areas of ulceration were noted which were focally covered by a white pseudomembrane. No bruit or thrill was perceived. Tooth #18 exhibited Class I mobility. The remainder of the intraoral examination revealed generalized mild gingival recession and gingivitis. The patient did not report paresthesia. The rest of the head and neck examination failed to reveal other skin, ocular, or scalp abnormalities or cervical lymphadenopathy.

Figure 1. The patient exhibits left facial asymmetry.

Figure 2. Oblique view of the patient’s face showing left asymmetry.

Figure 3. Photograph of the patient’s intraoral lesion.

Figure 4. Oblique view of the patient’s intraoral lesion.

Radiographic Findings

A panoramic radiograph of the area (Figure 5) was taken at the time of biopsy. An irregular radiolucent defect was observed in the left posterior mandible, at the site of the extracted tooth #17. The margins of the lesion were irregular and poorly defined in focal areas. The lesion approximated tooth #18, which showed loss of the lamina dura on the distal aspect. A CT scan demonstrated buccal and lingual cortical expansion with perforation.

Figure 5. The panoramic radiograph at the time of presentation to the oral and maxillofacial surgeon showed an ill-defined radiolucent lesion distal to tooth #18.

Incisional Biopsy and Photomicrographs

Following informed consent and local anesthesia, a 14-gauge needle was inserted into the lesion, but an aspirate could not be obtained during this procedure. An incisional biopsy was then taken from the attached gingiva, buccal to tooth #18, and the specimen was submitted for histopathologic examination. Microscopic examination revealed partially ulcerated oral mucosa infiltrated by sheets of pleomorphic neoplastic cells that appeared to be associated with the surface epithelium. (Figure 6)

Figure 6. Low-magnification photomicrograph of the biopsy specimen exhibiting the neoplastic population closely associated with the surface epithelium. There is no evidence of keratinization, but the tumor cells show deposition of a pigmented material within the cytoplasm (H&E stain).

The tumor cells had pleomorphic and hyperchromatic nuclei, prominent nucleoli, large numbers of mitotic figures, and melanin pigment within the cytoplasm (Figures 7, 8). Large areas of necrosis were also present. No keratinization or intercellular bridges were identified.

Figure 7. Medium-magnification photomicrograph of the biopsy specimen showing sheets of pleomorphic cells with prominent nucleoli and intracytoplasmic material (H&E stain).

Figure 8. High-magnification photomicrograph of the biopsy specimen showing numerous mitotic figures. No intercellular bridges are present (H&E stain).

Immunohistochemical stains for S-100 and HMB-45 were strongly and diffusely reactive within the neoplastic population (Figures 9, 10).

Figure 9. Low-magnification photomicrograph of the S-100 immunohistochemical stain.

Figure 10. High-power magnification photomicrograph of the S-100 immunohistochemical stain.