Yoshimura Yasuo, Sano Kenji, Isobe Ken-Ichi, Aoki Kaoru, Kito Munehisa, Kato Hiroyuki
Department of Orthopaedic Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan.
Department of Clinical Pathology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano390-8621, Japan.
Int J Surg Case Rep. 2016;21:111-4. doi: 10.1016/j.ijscr.2016.02.030. Epub 2016 Feb 27.
We describe an unusual case of a uniformly high-grade malignant solitary fibrous tumor (SFT) of the thigh with recurrence after wide resection in a 31-year-old man.
Our current case showed a long-term benign course before the operation, although the subcutaneous tumor was larger than 10cm at presentation. The SFT was diagnosed by needle biopsy, and wide resection was performed. Histological findings showed proliferation of capillaries surrounded by masses of spindle-shaped cells without any cytologic atypia, and the percentage of MIB-1-positive nuclei was 2.1%. However, a rapidly enlarging recurrent tumor was observed 11 months after the operation. A second wide resection for the recurrent tumor was performed. Histologically, the tumor cells uniformly displayed significant cytologic atypia and pleomorphism, and had 40-50 mitoses per 10 high-power fields. The proportion of MIB-1-positive nuclei was 48%. Consequently, the tumor was diagnosed as a SFT with malignant transformation.
The malignant transformation described in past studies showed high-grade areas within benign, low-grade, or intermediate-grade SFTs. Therefore, in contrast to our case, uniformly high-grade malignant histological findings at recurrence were not described.
Even if a tumor is non-malignant during the clinical course, as confirmed by tissue biopsy, the possibility of tumor progression to high-grade sarcoma at recurrence should be considered, and the treatment strategy should be determined carefully.
我们描述了一例罕见病例，一名31岁男性大腿部出现一例组织学分级均为高级别的恶性孤立性纤维瘤（SFT），在广泛切除术后复发。
我们的当前病例在手术前呈现出长期的良性病程，尽管皮下肿瘤在初诊时大于10cm。通过针吸活检诊断为SFT，并进行了广泛切除。组织学检查结果显示，毛细血管在梭形细胞团块周围增生，无任何细胞学异型性，MIB-1阳性核的百分比为2.1%。然而，术后11个月观察到肿瘤迅速复发且增大。对复发性肿瘤进行了第二次广泛切除。组织学上，肿瘤细胞均表现出明显的细胞学异型性和多形性，每10个高倍视野有40 - 50个有丝分裂象。MIB-1阳性核的比例为48%。因此，该肿瘤被诊断为发生恶性转化的SFT。
既往研究中描述的恶性转化表现为良性、低级别或中级别的SFT内出现高级别区域。因此，与我们的病例不同，既往未描述复发时组织学表现均为高级别恶性的情况。
即使肿瘤在临床病程中经组织活检证实为非恶性，也应考虑肿瘤复发时进展为高级别肉瘤的可能性，并谨慎确定治疗策略。
