A rare case of melanin-pigmented dentinogenic ghost cell tumor

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Dentinogenic ghost cell tumor (DGCT) is a rare benign mixed epithelial and mesenchymal odontogenic tumor. Some reports have described melanin deposition in odontogenic tumors, but this seems to be a very rare feature in DGCT. Melanocytes are widely distributed in the skin, the nervous system, and the oral mucosa (for example the buccal mucosa, tongue, gingiva, or hard palate, and the uveal tract) but do not appear in bone tissue under normal conditions. However, melanin deposition may be present as a rare subtype in calcifying odontogenic cyst (COC) arising in the jawbone, as described in the COC section of the 1992 WHO classification. Racial pigmentation may be of significance in terms of the occurrence of pigmented odontogenic lesions, as the majority of such cases have been reported in persons of color. Here we report a 44-year-old Japanese woman with an elastic soft mass in the lingual gingiva of the lower right canine region. After establishing a clinical diagnosis of mandibular tumor, a biopsy examination of the lesion was performed. Histopathological examination showed small ghost cell-like hard tissue in a myxomatous stroma. Marginal mandibulectomy was therefore performed. Histopathologically, the solid tumor was partly cystic and showed mainly ameloblastoma-like epithelial proliferation containing numerous ghost cells and dentinoid formation. Granules of dark brown melanin pigment were also evident in the epithelial dysplasia and ghost cells. The pathological diagnosis was a DGCT with melanin deposition. The patient’s postoperative course has been uneventful, and we have continued with regular follow-up.