家族性腺瘤样息肉病癌变术后伴腹腔内韧带样纤维瘤1例

A Case of Familial Adenomatous Polyposis with Postoperative Malignant Transformation Complicated by Intra-Abdominal Desmoid Tumor

摘要: 家族性腺瘤样息肉病(Familial Adenomatous Polyposis, FAP)是一种常染色体显性遗传疾病，由APC基因突变引发，导致结直肠内广泛腺瘤性息肉，40岁未干预者结直肠癌风险接近100%。韧带样型纤维瘤(desmoid tumor, DT))作为FAP的重要肠外并发症，发生率约10%~20%，多见于腹腔或腹壁，具有局部侵袭性，虽不转移但易侵犯重要脏器，导致脏器梗阻、缺血等并发症，是致死率仅次于结直肠癌的第二大因素。在影像学上极易与恶性肿瘤腹腔转移或淋巴结转移混淆，本文拟回顾性分析1例家族性腺瘤样息肉病癌变术后伴腹腔内韧带样纤维瘤病展示了这一诊断陷阱，并对其发病机制及病理、临床表现、影像学特征、治疗策略进行学习，强调了MRI在软组织分辨上的优势以及病理活检的重要性，对临床医生避免误诊和过度治疗(如不必要的再次根治性手术)具有警示和教育意义。

Abstract: Familial adenomatous polyposis (FAP) is an autosomal dominant inherited disorder caused by mutations in the APC gene, characterized by the development of numerous adenomatous polyps throughout the colorectum. Without prophylactic intervention, the lifetime risk of colorectal cancer approaches nearly 100% by the age of 40. Desmoid tumors (DTs), also known as desmoid-type fibromatosis, represent a major extraintestinal manifestation of FAP, with an incidence of approximately 10%~20%. They most commonly occur in the abdominal cavity or abdominal wall and exhibit locally aggressive behavior. Although DTs do not metastasize, they can invade adjacent vital organs, leading to complications such as organ obstruction and ischemia, and constitute the second leading cause of mortality in patients with FAP after colorectal cancer. Radiologically, intra-abdominal desmoid tumors are easily confused with malignant peritoneal metastases or lymph node metastases. In this study, we retrospectively analyze a case of intra-abdominal desmoid-type fibromatosis occurring after malignant transformation in a patient with familial adenomatous polyposis, illustrating this important diagnostic pitfall. Furthermore, we review the pathogenesis, pathological features, clinical manifestations, imaging characteristics, and therapeutic strategies of this condition. This case highlights the superiority of magnetic resonance imaging (MRI) in soft tissue characterization and underscores the critical role of pathological biopsy, providing important educational value for clinicians to avoid misdiagnosis and overtreatment, such as unnecessary repeat radical surgery.