The number of recognized sarcoma types harboring targetable molecular alterations continues to increase. Here we present 25 examples of a distinctive myofibroblastic tumor, provisionally termed "myxoid inflammatory myofibroblastic sarcoma," which might be related to inflammatory myofibroblastic tumor, and which occurred in 13 males (52%) and 12 females at a median age of 37 years (range: 7 to 79 years). Primary tumor sites were peritoneum (18 patients; 72%), paratesticular (2; 8%), chest wall (1), upper extremity (1), esophagus (1), retroperitoneum (1), and uterus (1). Nine peritoneal tumors (50%) were multifocal at presentation; all other tumors were unifocal. Tumors showed bland-to-mildly-atypical neoplastic myofibroblasts in a myxoid stroma, with prominent inflammatory infiltrates in 22 cases (88%). Most tumors showed delicate branching stromal vessels like those of myxoid liposarcoma, and most showed infiltrative growth through non-neoplastic tissue. Immunohistochemistry demonstrated expression of SMA (19/25 tumors; 76%), desmin (13/22; 59%), and CD30 (5/11; 45%), while ALK was expressed in 1 tumor (of 25; 4%) that was negative for ALK rearrangement. Sequencing of 11 tumors showed seven to harbor tyrosine kinase fusions (4 PDGFRB, 2 PML::JAK1, 1 SEC31A::PDGFRA). Two instead harbored hot spot KRAS mutations (G12V and Q61H), and 2 were negative for known driving alterations. Clinical follow-up was available for 18 patients (72%; median: 2.7 years; range: 4 mo-12.3 years). Nine patients (50%) were alive with no evidence of disease, 5 (28%) died of disease, and 4 (22%) were alive with disease. Seven patients (39%) experienced peritoneal relapse or distant metastasis. Two patients showed disease progression on conventional, nontargeted chemotherapy. The patient whose tumor harbored SEC31A::PDGFRA was treated after multiple relapses with imatinib and sunitinib therapy, with progression-free periods of 5 and 2 years, respectively. Despite its bland appearance, myxoid inflammatory myofibroblastic sarcoma harbors a significant risk for disseminated disease, particularly when it occurs in the peritoneum. Targeted therapy could be considered for patients with disseminated disease.

中文翻译：

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粘液样炎症性肌纤维母细胞肉瘤：25 例具有看似平淡的形态和攻击性临床行为的独特肉瘤的临床病理学分析。


具有可靶向分子改变的公认肉瘤类型的数量持续增加。在这里，我们展示了 25 个独特的肌纤维母细胞肿瘤的例子，暂时称为“粘液样炎性肌纤维母细胞肉瘤”，可能与炎性肌纤维母细胞肿瘤有关，发生在 13 名男性 (52%) 和 12 名女性中，中位年龄为 37 岁。范围：7 至 79 岁）。原发肿瘤部位为腹膜（18例；72%）、睾丸旁（2例；8%）、胸壁（1例）、上肢（1例）、食道（1例）、腹膜后（1例）和子宫（1例）。九个腹膜肿瘤（50%）在就诊时为多灶性；所有其他肿瘤都是单灶的。肿瘤在粘液样基质中显示出温和至轻度非典型的肿瘤性肌成纤维细胞，22 例（88%）有明显的炎症浸润。大多数肿瘤显示出像粘液样脂肪肉瘤一样脆弱的分支间质血管，并且大多数显示出通过非肿瘤组织的浸润性生长。免疫组织化学显示 SMA（19/25 个肿瘤；76%）、结蛋白（13/22；59%）和 CD30（5/11；45%）表达，而 ALK 在 1 个肿瘤（25 个肿瘤；4%）中表达ALK 重排结果为阴性。对 11 个肿瘤的测序显示，其中 7 个肿瘤含有酪氨酸激酶融合体（4 个 PDGFRB、2 个 PML::JAK1、1 个 SEC31A::PDGFRA）。相反，其中两个含有热点 KRAS 突变（G12V 和 Q61H），另外两个对于已知的驱动改变呈阴性。 18 名患者进行了临床随访（72%；中位时间：2.7 年；范围：4 个月至 12.3 年）。 9 名患者 (50%) 活着，没有任何疾病证据，5 名患者 (28%) 因疾病死亡，4 名患者 (22%) 带着疾病活着。 7 名患者（39%）出现腹膜复发或远处转移。两名患者在常规非靶向化疗后出现疾病进展。 肿瘤携带 SEC31A::PDGFRA 的患者在多次复发后接受伊马替尼和舒尼替尼治疗，无进展期分别为 5 年和 2 年。尽管其外观平淡无奇，但粘液样炎性肌纤维母细胞肉瘤具有播散性疾病的重大风险，特别是当它发生在腹膜时。对于患有播散性疾病的患者可以考虑靶向治疗。