Institute of Pathology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Krankenhausstrasse 8-10, 91054, Erlangen, Germany.
Virchows Arch. 2018 Sep;473(3):351-360. doi: 10.1007/s00428-018-2350-0. Epub 2018 Apr 5.
Although harmless, reactive and benign neoplastic myo-/fibroblastic proliferations represent a diagnostic challenge in routine surgical pathology practice as reflected by their frequency among consultation cases. In addition to resembling each other, the prototypical nodular fasciitis (NF) and NF-like lesions can be mistaken for low-grade or aggressive sarcomas. USP6 translocation was reported recently as the molecular driver and potential diagnostic marker of NF. We reviewed 71 lesions with a diagnosis of NF (n = 48) or NF-like myofibroblastic proliferations (n = 23) and screened them for USP6 translocation by fluorescence in situ hybridization (FISH). Only one third of NFs were correctly diagnosed by submitting pathologists while one third was initially judged as malignant. NF was mentioned in the differential diagnosis in only half of the cases. A high Ki67/mitotic index, misleading immunohistochemistry (false-positive h-caldesmon), and unusual sites/circumscription were main causes behind overdiagnosis as malignant. FISH analysis revealed USP6 translocation in 74.4% of NF cases. None of the reactive/reparative myofibroblastic proliferations showed USP6 translocation. NF is still significantly misdiagnosed by general surgical pathologists, with a higher tendency toward overdiagnosis of malignancy. Inclusion of NF in the differential diagnosis of any fibromyxoid soft tissue lesion and awareness of its diverse morphology are mandatory to avoid misdiagnoses with the risk of disastrous overtreatment. In the appropriate clinicopathological context, USP6 gene translocation is a valuable adjunct for diagnosis of NF, particularly in limited biopsies. Absence of the USP6 gene translocation in NF-like reparative pseudosarcomatous myofibroblastic proliferations underlines their reactive nature and distinguishes them from NF which is currently considered a benign neoplasm with a self-limiting "transient" growth phase.
虽然无害、反应性和良性的肌纤维母细胞性肿瘤增生在常规外科病理学实践中构成了诊断挑战，这反映在它们在会诊病例中的频率。除了彼此相似之外，典型的结节性筋膜炎（NF）和 NF 样病变可能被误诊为低级或侵袭性肉瘤。最近报道 USP6 易位是 NF 的分子驱动因素和潜在的诊断标志物。我们复习了 71 例诊断为 NF（n=48）或 NF 样肌纤维母细胞性增生（n=23）的病变，并通过荧光原位杂交（FISH）对它们进行 USP6 易位筛查。只有三分之一的 NF 被送检病理医生正确诊断，而三分之一的 NF 最初被判断为恶性。只有一半的病例在鉴别诊断中提到 NF。高 Ki67/有丝分裂指数、误导性的免疫组化（假阳性 h-caldesmon）和不常见的部位/边界是误诊为恶性的主要原因。FISH 分析显示 74.4%的 NF 病例存在 USP6 易位。无反应性/修复性肌纤维母细胞性增生显示 USP6 易位。普通外科病理医生仍明显误诊 NF，恶性过度诊断的倾向更高。在任何纤维粘液样软组织病变的鉴别诊断中纳入 NF，并意识到其多种形态，是避免误诊和灾难性过度治疗风险的必要条件。在适当的临床病理背景下，USP6 基因易位是 NF 诊断的有价值的辅助手段，特别是在有限的活检中。NF 样修复性假肉瘤性肌纤维母细胞性增生中不存在 USP6 基因易位，强调了它们的反应性本质，并将其与 NF 区分开来，NF 目前被认为是一种具有自限性“短暂”生长阶段的良性肿瘤。
