Ribosomes are responsible for the protein synthesis that maintains cellular homeostasis and is required for the rapid cellular division of cancer cells. However, the role of ribosome biogenesis mediators in the malignant behavior of tongue squamous cell carcinoma (TSCC) is unknown. In this study, we found that the expression of RIOK2, a key enzyme involved in the maturation steps of the pre-40S ribosomal complex, was significantly associated with poorer overall survival in patients with TSCC. Further, multivariate analysis revealed that RIOK2 is an independent prognostic factor (hazard ratio, 3.53; 95% confidence interval, 1.19–10.91). Inhibition of RIOK2 expression by siRNA decreased cell growth and S6 ribosomal protein expression in oral squamous cell carcinoma cell lines. RIOK2 knockdown also led to a significant decrease in the protein synthesis in cancer cells. RIOK2 has potential application as a novel therapeutic target for TSCC treatment.

Oral squamous cell carcinoma is generally characterized by poor prognosis, and biomarkers are needed for development and selection of therapy. The purpose of this study was to assess expression of actinin-4, which has been implicated in cancer invasion and metastasis, to determine its viability as a prognostic indicator in oral squamous cell carcinoma. Clinical factors and tumor samples immunohistochemically stained for actinin-4 were retrospectively investigated in 55 patients who underwent curative surgery for oral squamous cell carcinoma. Overall survival and disease-free survival were estimated by Kaplan-Meier analysis. Significant differences were detected using the Pearson’s chi-square and Fisher’s exact tests. Univariate and multivariate analyses were performed with the Cox regression model. No association was found between expression of actinin-4 and clinical factors, including age or sex, or histopathological factors, including vascular invasion, lymphatic invasion, stage, mode of invasion, or histological atypicality. Expression of actinin-4 showed a positive correlation with delayed cervical lymph node metastasis. Disease-free survival was significantly lower in patients who were positive for expression of actinin-4 (p=0.010); overall survival showed no difference between patients with or without expression of actinin-4, however. The results revealed that actinin-4 was an independent prognostic factor for disease-free survival. Expression of actinin-4 showed a 73% sensitivity and 68% specificity for prediction of delayed cervical lymph node metastasis. In conclusion, actinin-4 may potentially be a useful biomarker for prediction of delayed cervical lymph node metastasis.

Salivary gland tumors can also occur rarely in the retromolar area, though common near the junction of hard and soft palate, labial mucosa, and buccal mucosa. Most salivary gland tumors in the retromolar pad area are malignant and should be excised. The cystadenoma is a rare, benign, salivary gland tumor. Importantly, incomplete resection of this tumor can lead to recurrence or cervical lymph node metastasis. We reported herein a case of cystadenoma arising in the right retromolar pad area in a 63-year-old male patient who underwent reconstruction using a buccal fat pad flap (BFPF) after the surgical removal of the tumor with a 10-mm margin left a defect with bone exposure. No evidence of recurrence or complication was found at the postoperative, three-year follow-up.

Malignant melanoma demonstrates strikingly varied clinical presentations, on account of which it is often challenging to diagnose. We describe herein a rare case of amelanotic malignant melanoma (AMM) in the buccinator muscle presenting as a solitary mass. A middle-aged woman presented with a non-pigmented swelling under the right buccal mucosa. Magnetic resonance imaging (MRI) revealed a well-circumscribed lesion without local invasion. A needle biopsy did not establish the diagnosis and was instead interpreted as suggestive of a salivary gland tumor, reinforcing an initial impression of myoepithelioma. Histopathological analysis of an excised specimen revealed poorly defined, pleomorphic tumor cells and a scattering of melanin-containing cells. The diagnosis of AMM was established by integrating these histopathological features with the clinico-radiological findings and the immunohistochemical results, which were positive for HMB-45, S-100, and SOX10 and negative for cytokeratin. Whole-body positron-emission tomography-computed tomography found no primary lesion. Because tumor nests suggesting possible residual disease were observed near the resection margin, a wider, secondary excision including the affected portion of the buccal mucosa and overlying skin was performed together with neck dissection. Histopathological examination of the re-resection specimen showed no residual tumor, indicating that no malignant cells were identified in the adjacent oral mucosa or facial skin. The patient has remained disease-free for three years.

Fibrolipomas of the oral cavity are uncommon, and occurrence in the mandibular alveolar mucosa adjacent to the mental foramen is particularly rare. We report a 68-year-old woman who presented with a painless swelling of the right lower gingiva. Clinical and radiologic evaluation identified a well-circumscribed lipomatous lesion located 3 mm anterior to the right mental foramen. Computed tomography (CT) demonstrated a homogeneous low-density mass, and magnetic resonance imaging (MRI) showed high signal intensity on T1- and T2-weighted sequences with signal suppression on short Tau inversion recovery (STIR), findings consistent with a lipomatous tumor. Given the lesion’s close relationship to the mental neurovascular bundle, complete excision was performed via a subperiosteal approach to preserve the overlying mucosa and minimize risk to sensory function. Under local anesthesia, a triangular mucoperiosteal flap was elevated, and the tumor was removed en bloc. Intraoperatively, no adhesion to the mental nerve was observed. Histopathology revealed mature adipocytes embedded in a dense fibrous stroma, confirming the diagnosis of fibrolipoma. The postoperative course was uneventful, with no sensory deficits or recurrence during follow-up. This case underscores two clinical points. First, fibrolipoma in this location is rare and requires thorough imaging to distinguish it from other submucosal masses. Second, a subperiosteal approach permits complete resection while maintaining mucosal integrity and protecting adjacent neurovascular structures, thereby reducing postoperative morbidity. Our experience reinforces the importance of tailoring surgical strategy to the lesion’s anatomy in intraoral lipomatous tumors.