分類不能の歯肉原発悪性多形性腫瘍例

抄録

Unclassified/undifferentiated sarcomas are defined by the 2013 World Health Organization monograph as a heterogeneous group of sarcomas without evidence of a specific line of differentiation. Notably, malignant soft tissue tumors of the head and neck are extremely rare. We report a rare case of an unclassified malignant pleomorphic tumor of the gingiva.

A man in his early 50s was referred to our hospital by his primary care dentist for evaluation and treatment of an erosive lesion of the right upper gingiva that bled easily. We performed a lesional biopsy and with a presumptive diagnosis of a pleomorphic spindle-shaped malignant soft tissue tumor, right partial maxillectomy with extended resection of the gingival lesion was performed for further evaluation and diagnosis, as well as treatment. Based on the final histopathological findings, the tumor was diagnosed as an unclassified malignant pleomorphic tumor. The patient’s postoperative course was uneventful, without local recurrence or metastasis over a period of 12 months.

Few reports have described malignant soft tissue tumors of the head and neck, and treatment of these lesions involves extended resection. Currently, no standardized treatment protocol is established for unclassified/undifferentiated sarcomas of the head and neck, because extensive resection of lesions at these sites is associated with cosmetic or morphological factors that significantly affect the quality of life of the patients. Therefore, multimodal therapies are warranted for the management of malignant soft tissue tumors of the head and neck.

Further accumulation of cases is necessary to conclusively establish such standardized multimodality interventions.