Pigmented intraosseous odontogenic carcinoma of the maxilla: a pediatric case report and differential diagnosis.

We report a pigmented intraosseous odontogenic carcinoma of the maxilla occurring in a 6-year-old Japanese boy. Grossly, the tumor showed solid, gray-yellow, and markedly pigmented appearance. Histology showed neoplastic growths of atypical epithelial cells that occasionally contained melanin pigments. Melanocytes with dendritic processes were often found in the tumor cell clusters, and solitary or aggregated melanophages were scattered within the dense fibrovascular stroma. The tumor cells were diffusely positive for cytokeratins and epithelial membrane antigen, and focally positive for vimentin, neuron specific enolase, neurofilament protein, carcinoembryonic antigen, and amelogenin. Ultrastructural studies showed well-developed intercellular junctions, mainly desmosomes, and glycogen particles. In addition, some tumor cells contained melanosomes and/or a few neurosecretory granules. We consider that the present tumor suggests a close association of ectoderm, mesenchyma, and neuroectoderm in embryogenesis of the tooth, and can raise a diagnostic confusion with melanotic neuroectodermal tumor.