Cui J, Lu Y, Qiu Y, He X, Chen M, Zhang H Y
Department of Pathology, West China Hospital, Sichuan University, Chengdu 610041, China.
Zhonghua Bing Li Xue Za Zhi. 2023 Apr 8;52(4):364-369. doi: 10.3760/cma.j.cn112151-20221228-01074.
To investigate the clinicopathological features, immunophenotypes and molecular genetics of fibroma of tendon sheath (FTS). One hundred and thirty-four cases of FTS or tenosynovial fibroma diagnosed in the Department of Pathology, West China Hospital, Sichuan University, Chengdu, China from January 2008 to April 2019 were selected. The clinical and histologic features of these cases were retrospectively reviewed. Immunohistochemistry, fluorescence in situ hybridization (FISH) and reverse transcription-polymerase chain reaction (RT-PCR) were performed on the above cases. There were a total of 134 cases of FTS, including 67 males and 67 females. The patients' median age was 38 years (ranged from 2 to 85 years). The median tumor size was 1.8 cm (ranged from 0.1 to 6.8 cm). The most common site was the upper extremity (76/134, 57%). Follow-up data was available in 28 cases and there was no detectable recurrence. Classic FTS (114 cases) were well-defined and hypocellular. A few spindle-shaped fibroblasts were scattered in the dense collagenous sclerotic stroma. Characteristically elongated slit-like spaces or thin-walled vessels were observed. Most of cellular FTSs (20 cases) were well-defined and the area with increased cellularity of the spindle cells coexisted with classic FTS. There were occasional mitotic figures, but no atypical mitotic figures. Immunohistochemistry was performed in 8 cases of classic FTS and most cases were positive for SMA (5/8). Immunohistochemistry was also performed in 13 cases of cellular FTS and showed 100% positive rate for SMA. FISH was conducted on 20 cases of cellular FTS and 32 cases of classical FTS. USP6 gene rearrangement was found in 11/20 of cellular FTS. Among 12 cases of CFTS with nodular fasciitis (NF)-like morphological feature, 7 cases showed USP6 gene rearrangement. The rearrangement proportion of USP6 gene in cellular FTS without NF-like morphological features was 4/8. By contrast, 3% (1/32) of the classic FTS showed USP6 gene rearrangement. RT-PCR was performed in those cases with detected USP6 gene rearrangement and sufficient tissue samples for RT-PCR. The MYH9-USP6 fusion gene was detected in 1 case (1/8) of the cellular FTSs, while no target fusion partner was detected in the classic FTS. FTS is a relatively rare benign fibroblastic or myofibroblastic tumor. Our study and recent literature find that some of the classic FTS also show USP6 gene rearrangements, suggesting that classical FTS and cellular FTS are likely to be at different stages of the same disease (spectrum). FISH for USP6 gene rearrangement may be used as an important auxiliary diagnostic tool in distinguishing FTS from other tumors.
探讨腱鞘纤维瘤（FTS）的临床病理特征、免疫表型及分子遗传学特点。选取2008年1月至2019年4月在四川大学华西医院病理科诊断的134例FTS或腱鞘滑膜纤维瘤病例。对这些病例的临床和组织学特征进行回顾性分析。对上述病例进行免疫组织化学、荧光原位杂交（FISH）及逆转录-聚合酶链反应（RT-PCR）检测。FTS病例共134例，其中男性67例，女性67例。患者中位年龄为38岁（范围2至85岁）。肿瘤中位大小为1.8 cm（范围0.1至6.8 cm）。最常见部位为上肢（76/134，57%）。28例有随访资料，均未发现复发。经典型FTS（114例）边界清晰，细胞稀少。少数梭形纤维母细胞散在于致密的胶原硬化间质中。可见特征性的细长裂隙样间隙或薄壁血管。大多数细胞型FTS（20例）边界清晰，梭形细胞增多区域与经典型FTS并存。偶见核分裂象，但无非典型核分裂象。对8例经典型FTS进行免疫组织化学检测，多数病例SMA阳性（5/8）。对13例细胞型FTS进行免疫组织化学检测，SMA阳性率为100%。对20例细胞型FTS和32例经典型FTS进行FISH检测。细胞型FTS中11/20发现USP6基因重排。12例具有结节性筋膜炎（NF）样形态特征的经典型FTS中，7例显示USP6基因重排。无NF样形态特征的细胞型FTS中USP6基因重排比例为4/8。相比之下，3%（1/32）的经典型FTS显示USP6基因重排。对检测到USP6基因重排且有足够组织样本用于RT-PCR的病例进行RT-PCR检测。细胞型FTS中有1例（1/8）检测到MYH9-USP6融合基因，而经典型FTS未检测到目标融合伴侣。FTS是一种相对罕见的良性纤维母细胞或肌纤维母细胞肿瘤。我们的研究及近期文献发现，部分经典型FTS也显示USP6基因重排，提示经典型FTS和细胞型FTS可能是同一疾病（谱系）的不同阶段。USP6基因重排的FISH检测可作为鉴别FTS与其他肿瘤的重要辅助诊断工具。
