case_images: PMC5349031_01
case_images: Panoramic radiograph showing a radiopaque lesion in the right oral mucosa
  (arrow)
case_images: jaos-18-01-0100-g01.jpg
case_images: PMC5349031_01_jaos-18-01-0100-g01.jpg
case_images: f01
case_images: Epithelial acanthosis and brownish-black pigment deposits in the submucosal region
  (arrow) (Hematoxylin and eosin, x100)
case_images: jaos-18-01-0100-g02.jpg
case_images: PMC5349031_01_jaos-18-01-0100-g02.jpg
case_images: f02
case_images: Histopathological examination revealed epithelial acanthosis and brownish-black pigment deposits in the submucosa surrounded by a lymphocyte inflammatory infiltrate (Figure 2), and multinucleated giant cells phagocyting these pigments (Figure 3).
case_images: Multinucleated giant cells phagocyting brownish-black pigments (Hematoxylin and
  eosin, x400)
case_images: jaos-18-01-0100-g03.jpg
case_images: PMC5349031_01_jaos-18-01-0100-g03.jpg
case_images: f03
case_images: Histopathological examination revealed epithelial acanthosis and brownish-black pigment deposits in the submucosa surrounded by a lymphocyte inflammatory infiltrate (Figure 2), and multinucleated giant cells phagocyting these pigments (Figure 3).
case_images: Impregnation of muscle cells by brownish-black pigments (Hematoxylin and eosin,
  x400)
case_images: jaos-18-01-0100-g04.jpg
case_images: PMC5349031_01_jaos-18-01-0100-g04.jpg
case_images: f04
case_images: Muscle cells were impregnated in the deeper layers (Figure 4).