case_images: PMC7780343_01
case_images: Clinical photographs of oral melanoacanthoma.. Macular brown pigmentation with irregular margins involving (
  a) upper and lower attached and free gingivae; (
  b) upper labial mucosa; (
  c) lower labial mucosa.
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case_images: ACTH 26 pg/ml and cortisol 184.9 nmol/L. A physical examination revealed no skin pigmentation and an extraoral examination showed no significant findings. An intraoral examination showed asymptomatic, diffuse, smooth, macular blackish-brown pigmentation with irregular margins on both the upper and lower attached and free gingivae, and upper and lower labial mucosae ( Figures 1a-1c).
case_images: Microphotograph of the stained biopsy tissue.. Microphotograph of hematoxylin and eosins stained tissue shows the parakeratinized, hyperplastic, stratified squamous epithelium with acanthosis, and long rete ridges. Many benign dendritic melanocytes with dendritic processes can be seen distributed in the epithelium, as well as melanin deposits in the lamina propria.
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case_images: In addition, melanin pigmentation of basal cell layer was noted with evidence of melanin deposits in the lamina propria ( Figure 2).
case_images: Microphotograph of Melan-A stained biopsy tissue.. Microphotograph of Melan-A stained biopsy tissue shows melanotic hyperplasia in the epithelium.
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case_images: A microphotograph of Melan-A stained tissue shows melanotic hyperplasia in the epithelium ( Figure 3).
case_images: Follow-up clinical photograph.. An eight-month-follow up visit revealed that the brown pigmentation had faded gradually.
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case_images: At 8-months follow up, the lesion had gradually faded ( Figure 4).