硬纖維瘤之診斷挑戰與個別化治療：兩病例報告

趙浩均¹、盧嘉文²、李香瑩²

¹高雄醫學大學附設中和紀念醫院一般醫學科；

²高雄醫學大學附設中和紀念醫院泌尿科

Diagnostic Challenges and Individualized Management of Desmoid Fibromatosis: A Two-Case Report

Hao‑Chun Chao¹, Kevin Lu², Hsiang‑Ying Lee²

¹Department of General Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan;

²Department of Urology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan

Introduction:

Desmoid fibromatosis (DF) is a rare, locally aggressive, yet non-metastasizing mesenchymal neoplasm characterized by the clonal proliferation of myofibroblastic spindle cells ADDIN EN.CITE  ADDIN EN.CITE.DATA (1, 2). In the urological and retroperitoneal spaces, DF remains clinically challenging. Its presentation is remarkably heterogeneous, often mimicking other neoplastic lesions ADDIN EN.CITE <EndNote><Cite><Author>Nam</Author><Year>2023</Year><RecNum>3</RecNum><DisplayText>(3)</DisplayText><record><rec-number>3</rec-number><foreign-keys><key app="EN" db-id="awaawt95dfswpwee5zc5wxagadvf0t5tpv5x" timestamp="1774458932">3</key></foreign-keys><ref-type name="Journal Article">17</ref-type><contributors><authors><author>Nam, Kyung Han</author><author>Kim, Bomi</author></authors></contributors><titles><title>Intra-abdominal desmoid fibromatosis mimicking tumour recurrence after the operation: A case series</title><secondary-title>Malaysian Journal of Pathology</secondary-title></titles><periodical><full-title>Malaysian Journal of Pathology</full-title></periodical><pages>111–122</pages><volume>45</volume><number>1</number><dates><year>2023</year></dates><urls></urls></record></Cite></EndNote>(3). In this case report, we present two distinct cases of DF to highlight these diagnostic pitfalls, potential distinct pathogenic pathways, and management decisions.

Case presentation:

Case 1:

A 24-year-old woman with a complex oncologic history of previously treated pilocytic astrocytoma, endometrial carcinoma, and sigmoid adenocarcinoma, as well as left renal cell carcinoma treated with nephrectomy, and multiple colonic adenomas suggestive of an underlying hereditary polyposis syndrome, was incidentally found to have a newly developed retroperitoneal mass on surveillance imaging. Abdominal computed tomography (CT) revealed a heterogeneous lesion at the left renal bed with suspected invasion of the splenic flexure, raising strong concern for recurrent malignancy. CT-guided biopsy suggested desmoid fibromatosis. In consideration of the diagnostic uncertainty and the potential risk of future bowel complications, she underwent open retroperitoneal tumor excision with left colonic resection and lymph node sampling. Final pathology confirmed desmoid fibromatosis, with no evidence of lymph node metastasis.

Case 2:

A 33-year-old woman with irregular menstruation was incidentally found to have a perivesical mass during ultrasonographic evaluation in her first pregnancy. Abdominal CT revealed a tumor closely abutting the inferior bladder wall, initially favoring endometriosis. CT-guided biopsy demonstrated a spindle cell neoplasm consistent with desmoid fibromatosis, supported by nuclear beta-catenin expression. She subsequently underwent open excision of the perivesical tumor, and final pathology confirmed desmoid fibromatosis with a positive surgical margin (R1). Surveillance imaging 3 months later detected local recurrence, and follow-up CT showed interval enlargement of the recurrent lower abdominal mass to 8.6 cm with invasion of the adjacent abdominal wall. Although she remained asymptomatic, repeat open excision of the perivesical tumor with abdominal wall repair using mesh was performed given the enlarging lesion, its proximity to the reproductive organs, and her fertility needs. Pathology again confirmed desmoid fibromatosis, this time with negative surgical margins.

Discussion:

Diagnosing desmoid fibromatosis (DF) remains challenging, with reported misdiagnosis rates of up to 30–40% ADDIN EN.CITE  ADDIN EN.CITE.DATA (2), largely due to its tendency to mimic other diseases depending on tumor location and personal history. In Case 1, a newly developed mass near the left renal bed in a patient with multiple prior malignancies strongly suggested tumor recurrence, whereas in Case 2, a perivesical lesion in a postpartum patient with a history of irregular menstruation initially indicated a gynecologic lesion such as endometriosis. These diagnostic pitfalls underscore the critical role of core needle biopsy and expert pathologic review. Specifically, immunohistochemical staining demonstrating nuclear β-catenin expression is essential to definitively diagnose DF and avoid inappropriate radical treatments.

Biologically, these cases highlight two distinct pathogenic pathways of DF. Case 1 raises strong suspicion for familial adenomatous polyposis (FAP)-associated DF, in which germline APC mutations lead to dysregulated β-catenin accumulation and predispose to intra-abdominal fibromatosis. In contrast, Case 2 represents sporadic DF, most commonly driven by somatic CTNNB1 mutations. The association with pregnancy supports estrogen and trauma related proliferative trigger ADDIN EN.CITE  ADDIN EN.CITE.DATA (4). Despite similar histologic features, DF encompasses heterogeneous molecular mechanisms with distinct clinical implications.

The management of DF has shifted from routine surgical resection toward an initial strategy of active surveillance, given its unpredictable natural history and high postoperative recurrence rates ADDIN EN.CITE  ADDIN EN.CITE.DATA (1, 2). Nevertheless, our cases demonstrate specific scenarios where surgery remains necessary. In Case 1, surgical intervention was justified by diagnostic uncertainty and the risk of bowel complications. In Case 2, while active surveillance is generally favored even after an R1 resection, the rapid enlargement and its proximity to reproductive organs necessitated a repeat excision. Abdominal wall reconstruction with mesh provided structural stability while preserving future fertility potential. For unresectable or recurrent disease, systemic therapies including tyrosine kinase inhibitors, chemotherapy, and gamma-secretase inhibitors offer effective non-surgical options ADDIN EN.CITE  ADDIN EN.CITE.DATA (1, 2). Overall, management of retroperitoneal and pelvic DF requires a highly individualized and multidisciplinary approach.

Highlights:

1.          Desmoid fibromatosis is a great mimicker that often leads to diagnostic pitfalls, making tissue diagnosis essential.

2.          Desmoid fibromatosis represents biologically heterogeneous disease with both hereditary (APC-driven) and sporadic (mostly CTNNB1-driven) forms.

3.          Surgery remains indicated in selected clinical scenarios despite active surveillance trend.

Reference:

 ADDIN EN.REFLIST 1.     Kasper B, Baldini EH, Bonvalot S, Callegaro D, Cardona K, Colombo C, et al. Current Management of Desmoid Tumors: A Review. JAMA Oncol. 2024;10(8):1121–8.

2.     Riedel RF, Agulnik M. Evolving strategies for management of desmoid tumor. Cancer. 2022;128(16):3027–40.

3.     Nam KH, Kim B. Intra-abdominal desmoid fibromatosis mimicking tumour recurrence after the operation: A case series. Malaysian Journal of Pathology. 2023;45(1):111–22.

4.     Drabbe C, van der Graaf WTA, Husson O, Bonenkamp JJ, Verhoef C, van Houdt WJ. Pregnancy-associated desmoid fibromatosis: A Dutch multi-centre retrospective study. Eur J Surg Oncol. 2023;49(5):921–7.