PMC8064661_01
(A) Oral examination at presentation: dark pigmented macule of the soft palate associated with an area of ulceration. (B) Biopsy specimen macroscopic view. (C) After 1 year, the lesion had increased in size.
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Intraoral examination revealed a 40 mm x 20 mm painless, asymmetric, darkly pigmented macule on the soft palate, with irregular borders and focal ulceration (Figure 1A). The clinical diagnosis was melanoma; hence, an intralesional biopsy was performed (Figure 1B). After a 1-year follow-up, the lesion had increased in size (Figure 1C).
Histopathology of the pigmented carcinoma in situ. (A-C) In situ carcinoma with several dendritic melanocytes interspersed throughout the tumor (H&E stain, original magnification x400, respectively). (D) Increased cell proliferation in the entire epithelial thickness (immunohistochemistry, Ki-67, original magnification x100). (E) Tumor epithelial cells were positive for pancytokeratin (original magnification x100). (F) Fontana Masson staining revealed little transfer of pigment to dysplastic epithelial cells (original magnification x100). (G) and (H) Single dendritic melanocytes are immunostained, respectively, for Melan A and HMB-45 (original magnification x400).
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The histopathological features were full-thickness epithelium atypia and a minimal keratinization tendency toward the surface (Figure 2A to C). Masson staining revealed little transfer of pigment to dysplastic epithelial cells (Figure 2F). Mild melanin incontinence was found. Immunohistochemical staining within the tumor epithelial cells was positive for pancytokeratin (Figure 2E). Increased epithelial cells proliferation throughout the entire tumor thickness was highlighted by Ki-67 immunomarking (Figure 2D). The dendritic cells were selectively stained for S-100, HMB-45, and Melan-A (Figure 2G and H).