Abstract：
Superficial fibromas are a group of mesenchymal spindle cell lesions with pathomorphological heterogeneity and diverse molecular backgrounds. In part, they may be indicators of an underlying syndrome. Among the best-known entities of superficial fibromas is Gardner fibroma, a plaque-like benign tumor, which is associated with APC germline mutations and occurs in patients with familial adenomatosis polyposis (Gardner syndrome). Affected patients also have an increased risk to develop desmoid fibromatosis (DTF), a locally aggressive neoplasm of the deep soft tissue highly prone to local recurrences. Although a minority of DTFs occur in the syndromic context and harbor APC germline mutations, most frequently their underlying molecular aberration is a sporadic mutation in Exon 3 of the CTNNB1 gene. Up to date, a non-syndromic equivalent to Gardner fibroma carrying a CTNNB1 mutation has not been defined. Here, we present two cases of (sub-)cutaneous tumors with a hypocellular and collagen-rich Gardner fibroma-like appearance and pathogenic, somatic CTNNB1 mutations. We aim to differentiate these tumors from other fibromas according to their histological appearance, immunohistochemical staining profile and underlying somatic CTNNB1 mutations. Furthermore, we distinguish them from locally aggressive desmoid fibromatosis regarding their biological behavior, prognosis and indicated therapeutic strategies. Consequently, we call them CTNNB1-mutated superficial fibromas as a sporadic counterpart lesion to syndromic Gardner fibromas.
摘要：
浅表纤维瘤是一组间充质梭形细胞病变，具有病理形态学异质性和不同的分子背景。在某种程度上,它们可能是潜在综合征的指标。最著名的浅表性纤维瘤实体是Gardner纤维瘤，斑块样良性肿瘤,与APC种系突变相关，发生在家族性腺瘤性息肉病（Gardner综合征）患者中。受影响的患者发生纤维瘤病（DTF）的风险也增加，深部软组织的局部侵袭性肿瘤很容易局部复发。尽管少数DTF发生在综合征背景下，并带有APC种系突变，最常见的潜在分子畸变是CTNNB1基因外显子3的偶发性突变。到目前为止,携带CTNNB1突变的Gardner纤维瘤的非综合征等同物尚未定义。这里,我们介绍了2例（下）皮肤肿瘤，具有低细胞和富含胶原蛋白的Gardner纤维瘤样外观和致病性，体细胞CTNNB1突变。我们的目标是根据其组织学外观将这些肿瘤与其他纤维瘤区分开来，免疫组织化学染色谱和潜在的体细胞CTNNB1突变。此外，我们将它们与局部侵袭性纤维瘤病的生物学行为区分开来，预后和治疗策略。因此,我们将CTNNB1突变的浅表纤维瘤称为综合征Gardner纤维瘤的零星对应病变。
