Infantile myofibromatosis (IM), which is typically diagnosed in young children, comprises a wide clinical spectrum ranging from inconspicuous solitary soft tissue nodules to multiple disseminated tumors resulting in life-threatening complications. Familial IM follows an autosomal dominant mode of inheritance and is linked to PDGFRB germline variants. Somatic PDGFRB variants were also detected in solitary and multifocal IM lesions. PDGFRB variants associated with IM constitutively activate PDGFRB kinase activity in the absence of its ligand. Germline variants have lower activating capabilities than somatic variants and, thus, require a second cis-acting hit for full receptor activation. Typically, these mutant receptors remain sensitive to tyrosine kinase inhibitors such as imatinib. The SIOPE Host Genome Working Group, consisting of pediatric oncologists, clinical geneticists and scientists, met in January 2020 to discuss recommendations for genetic testing and surveillance for patients who are diagnosed with IM or have a family history of IM/PDGFRB germline variants. This report provides a brief review of the clinical manifestations and genetics of IM and summarizes our interdisciplinary recommendations.

婴儿肌纤维瘤病 (IM) 通常在幼儿中被诊断出来，其临床范围很广，从不显眼的孤立性软组织结节到导致危及生命的并发症的多个播散性肿瘤。家族性 IM 遵循常染色体显性遗传模式，并与PDGFRB种系变异有关。在孤立性和多灶性 IM 病变中也检测到体细胞PDGFRB变异。PDGFRB与 IM 相关的变体在没有其配体的情况下组成性地激活 PDGFRB 激酶活性。种系变体的激活能力低于体细胞变体，因此需要第二次顺式作用才能完全激活受体。通常，这些突变受体对酪氨酸激酶抑制剂（如伊马替尼）保持敏感。由儿科肿瘤学家、临床遗传学家和科学家组成的 SIOPE 宿主基因组工作组于 2020 年 1 月举行会议，讨论对诊断为 IM 或有 IM/ PDGFRB种系变异家族史的患者进行基因检测和监测的建议。本报告简要回顾了 IM 的临床表现和遗传学，并总结了我们的跨学科建议。