PMC8387067_01
A - Tumor was found to involve the retromolar trigon (Left), extending laterally to the buccal mucosa and gingivobuccal sulcus and superiorly to the alveolar process and the hard and soft palates; B - A contrast-enhanced CT scan (Axial section) revealed a soft tissue mass in the left RMT, involving the body and ramus of mandible (left side) and the upper alveolus.
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Physical examination revealed a pigmented proliferative mass involving the gingival surface of the retromolar trigon, extending laterally to the buccal mucosa and gingivobuccal sulcus and superiorly to the alveolar process of the maxilla (Figure 1A). This mass involved the maxillary alveolus and palate without erosion of the palatal bone (Figure 1B).
Photomicrographs of the tumor. A - Section showing intact squamous epithelium and diffuse infiltration of the subepithelium by tumor cells (H&E, 40x); B - High power view showing round and spindle cells with prominent nucleoli, and melanin in the cells (H&E, 400x); C - Immunohistochemistry for Melanin A showing strong positivity in the tumor cells (200x); D - Immunohistochemistry for S-100 showing strong positivity in tumor cells (400x).
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Immunohistochemistry showed strong positivity for Melanin A and S-100 in the tumor cells (Figure 2A,B,C,D).
A - Intraoperative view showing wide local excision of the tumor along with left segmental mandibulectomy and infrastructural maxillectomy; B - Surgical specimen after the excision of the tumor; C - Harvation of the pectoralis major myocutaneous flap (left side) for soft tissue reconstruction.
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Wide local excision along with left segmental mandibulectomy and infrastructural maxillectomy was performed (Figure 3A). The tumor was 5.6 x 3.5 x 4.9 cm in size and weighed 62.2 g (Figure 3B). The defect was reconstructed with pectoralis major myocutaneous flap, spreading from the palatal margin to the floor of the mouth (Figure 3C).
Complete closure of the surgical defect with pectoralis major myocutaneous flap six weeks after the surgery.
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He has been on regular follow-up for the past 24 months and found asymptomatic without the recurrence of the disease (Figure 4).