A UNIQUE CASE OF AMELOBLASTOMA MIMICKING A MALIGNANT LESION

Publication date: January 2019

Source: Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology, Volume 127, Issue 1

Author(s): S. VIJAYAN, S.M. STEWARD-THARP, S.L. SOUSA MELO, V. ALLAREDDY, S. ANAMALI-ALLAREDDY

Background

Ameloblastoma is a true neoplasm of odontogenic epithelium.^1,2 It is a locally invasive, slow-growing, and persistent tumor.^1-4 It is among the most common odontogenic tumors.^1,2 Ameloblastoma can arise from dental lamina, dental organ, epithelial lining of odontogenic cyst, or basal cells of oral mucosa.^1,2

Clinical and Radiologic Findings

A 56-year-old female patient was referred for evaluation of a slow-growing, long-standing right mandibular swelling. The area was painful at times, with paresthesia of right lower lip. The patient lived in an assisted home and had a poor recall of her history because of mental illnesses. Axial computed tomogrphy (CT) of the head and neck region was performed after administration of 50 mL of Isovue-370 IV contrast. There was a large, well-defined, mixed entity on the right side of the mandible, extending approximately from the second molar region and crossing the midline to the left mandibular canine region. In the anterior region of the mandible, the entity presented a fine sunray appearance.

Differential or Definitive Interpretation

On the basis of radiographic findings osteosarcoma, ameloblastoma, keratocystic odontogenic tumor, and giant cell granuloma were considered in the differential diagnosis. Osteosarcoma was determined to be the diagnosis because of the unique sunray appearance, history of smoking (0.5 pack/day for 40 years [20 pack-years]), pain, and paresthesia. Initial biopsy analyses were inconclusive because of the nonpathognomonic features. Findings on analysis of the final excisional biopsy specimen, however, were consistent with an ameloblastoma, with an acanthomatous pattern.^1,3

Discussion/Conclusions

The imaging findings, such as the classic sunray appearance; location of the expansile, destructive lesion in the anterior portion of the mandible; and clinical findings of paresthesia of lip, intermittent pain, and history of smoking led to the formation of an aggressive neoplastic entity. However, the slow-growing nature of the lesion favored diagnosis of a benign neoplastic entity. Ameloblastomas may often mimic other benign lesions, but this is a unique case of an ameloblastoma presenting malignant features, in particular the acanthomatous pattern, is one of the rare types.³

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