A Case Report of Superficial Solitary Fibrous Tumor in the Right Parotideomasseteric Region

Solitary fibrous tumors (SFTs) are rare mesenchymal tumors that occur in various soft tissues and organs throughout the body. Superficial SFTs in the head and neck region are uncommon and reports of such cases are limited. An elderly Japanese woman in her 80s presented to our clinic with a smooth mass in the right parotideomasseteric region. Ultrasonography and magnetic resonance imaging revealed a well-defined subcutaneous mass measuring 20 mm. For a definitive diagnosis and treatment, surgical resection was performed under local anesthesia. Intraoperatively, a brown-colored tumor was identified beneath the skin, without surrounding tissue adhesion, and was completely excised. Immunohistochemistry, revealing the expression of STAT6, confirmed the diagnosis of SFT. Based on the SFT risk classification, this case was classified into the low-risk group, and no recurrence occurred during the 4 year postoperative period. According to the 2020 World Health Organization Classification of Soft Tissue Tumors, SFTs belong to the intermediate category with recurrence potential. In previous studies, cases of positive margins and recurrence have been reported in superficial SFTs, and SFTs may show benign features on clinical presentation but require precise surgical manipulation. Therefore, it is crucial for otolaryngologists to gain a comprehensive understanding of this tumor for appropriate treatment.