In routine pathological diagnoses of oral squamous cell carcinoma （SCC）, histopathological factors such as invasive pattern are assessed to determine the prognosis. In Japan, the Yamamoto–Kohama （YK） classification is generally used. The pattern of infiltrating growth （INF） and tumor budding are recently used as well. Moreover, the AJCC cancer staging manual （8th edition） now lists the worst pattern of invasion （WPOI）-5 as a validated outcome predictor for oral cancer. In this study, we investigated the characteristics of the YK classification, INF, tumor budding, and WPOI-5 with respect to their usefulness as prognostic indicators for pT1/T2 tongue SCC. Three oral pathologists evaluated invasive patterns independently. The individual SCC cases classified as YK-4C, INFc, tumor budding ＞5, or WPOI-5 showed high lymph node metastatic rate and low survival rate, related to increasing risks of poor prognosis. Additionally, the prognoses among these four groups showed no statistical differences, therefore the usefulness of these patterns as prognostic indicators is likely to be equivalent. Cross tabulation indicated that the YK classification, INF, and tumor budding were mutually correlated, and that WPOI-5 might be a histopathological factor that differed from the other three criteria. By simultaneous assessment of these four criteria in each SCC case, we found that most cases met multiple criteria of YK-4C, INFc, tumor budding ＞5, and WPOI-5. Therefore, we concluded that it is effective to apply multiple invasive patterns, specifically the combined use of WPOI-5 and another criterion, to more accurately predict the prognosis of pT1/T2 tongue SCC.

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We report a case of pigmented nevi with large masses in the maxillary and mandibular gingiva.
Case: A 43-year-old man presented with a black spot on the left maxillary and mandibular gingiva since childhood, and a mass formation in the same area from his twenties. He was referred to our hospital in September 2005. After self-interruption of his consultation two times, the patient consulted us again in April 2016 due to augmentation of the masses. The lobular and pigmented masses had smooth surfaces, were irregular, and were elastic hard in the left maxillary and mandibular gingiva. No abnormal bone resorption was revealed by panoramic radiography and CT. A biopsy was performed to confirm the definitive diagnosis under local anesthesia, and a histopathological examination showed intradermal type pigmented nevus. The patient does not wish surgical treatment and is still under observation without specific treatment.

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Acinic cell carcinoma derived from minor salivary glands is an extremely rare malignancy of the salivary glands. We report a case of a 69-year-old female who developed acinic cell carcinoma derived from the minor salivary glands. The patient visited our department with the chief complaint of the sensation of a mass in the right buccal mucosa. MRI showed a 25×20mm mass, and the tumor was excised under general anesthesia. Histopathological examination showed proliferation of cancer cells close to the minor salivary glands, and serous acinar cells accounted for a majority of the cancer cells. No evidence of any recurrence or metastasis was observed during the 20-month follow-up period.

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