Malignant ameloblastoma: a challenging diagnosis

Abstract

Ameloblastoma is an uncommon and locally aggressive, benign, odontogenic tumor, with local recurrence when not adequately excised. A rare variant of this neoplasm with the benign features but accompanied with metastases has been described. This rare variant is malignant ameloblastoma and is known to have a poor prognosis. We present the case of a young woman who had recurrent mandibular tumors, which were resected twice and histologically reported as ameloblastoma. Four years later, she presented with pulmonary metastasis and atelectasis. A review of the literature on this very rare neoplasm was also performed.

Keywords: Ameloblastoma; Mediastinum; Neoplasm Metastasis; Pulmonary Atelectasis.

Figure 1. Gross view of the neoplasm. A – The tumor (T) attached to the left lung (L) and the parietal pericardium (P); B – The cut surface of the tumor shows a greyish-white mass attached to the lung surface.

Figure 2. Photomicrography of the tumor. A – Nests and trabeculae of malignant cells show peripheral palisading of darkly staining cells with loose cells in the center (H&E, 250X); B and C – High power view showing stellate cells having a reticular appearance, and palisading columnar to polygonal cells at the periphery (H&E, 400X).

Figure 3. Photomicrography of the tumor. A, B and C – Infiltration of the trachea and bronchi by the malignant cells (H&E, 250X); D – A nest of tumor cells within the lung parenchyma (H&E, 250X).