Breast Fibromatosis in a Patient With a History of Treated Breast Cancer: A Case Report

Desmoid tumors are benign mesenchymal neoplasms that originate from muscular fasciae and aponeuroses. Breast involvement is exceptionally rare, accounting for less than 0.2% of all breast tumors. A 41-year-old woman with a history of right-sided invasive ductal carcinoma (IDC) diagnosed in 2022 underwent breast-conserving surgery (BCS) and axillary lymph node dissection (ALND), followed by adjuvant chemotherapy, radiotherapy, and daily tamoxifen (20 mg). The tumor measured 3.5 cm at its greatest dimension, was grade 2, estrogen receptor (ER)-positive, progesterone receptor (PR)-positive, HER2 negative, and had a Ki-67 proliferation index of 25%. Histologic examination revealed a cribriform growth pattern without associated ductal carcinoma in situ (DCIS) or lymphovascular invasion (LVI), and one of nine axillary lymph nodes was positive for metastasis. In 2023, a total abdominal hysterectomy with bilateral salpingo-oophorectomy was performed for ovarian suppression. During routine surveillance in 2024, a new mass was detected at the 2 o’clock position in the right breast. Two core needle biopsies performed over 6 months confirmed fibromatosis. Ongoing tumor enlargement and severe pain, despite radiotherapy, led to a wide local excision. Breast fibromatosis can closely mimic carcinoma both clinically and radiologically, and histologic analysis remains essential for definitive diagnosis. Complete surgical excision with negative margins remains the treatment of choice.

Background/Objectives: Intra-oral aggressive fibromatosis (IOAF) is a rare, locally invasive soft tissue tumor originating from fibroblasts. Despite its benign histological nature, IOAF exhibits a high recurrence rate and presents significant diagnostic and therapeutic challenges. This systematic review aims to synthesize the available literature on IOAF, focusing on clinical presentation, radiological and histological features, treatment modalities, and recurrence rates. Methods: A comprehensive systematic search was conducted, following PRISMA guidelines, across Pubmed, Cochrane, and ScienceDirect for case reports and series detailing IOAF published up to October 2025. This review was registered with PROSPERO (CRD42024586634). Data were extracted on demographics, clinical presentation, radiographic and histological findings, treatment strategies, and follow-up outcomes. Quality of included studies was assessed using the Joanna Briggs Institute (JBI) tools. Results: A total of 27 studies were included, encompassing 33 cases. IOAF predominantly affected males (54.5%) with a mean age of 13.15 years. The mandible was the most common site (69.7%). Painless swelling was the most frequent clinical feature (72.7%). Radiological findings were primarily ill-defined radiolucency in 54.5% of the cases. Histopathologically, spindle-shaped fibroblasts and collagen fibers were present in 90% of cases. En bloc resection was the most common treatment (60.6%), followed by excision (27.3%). Recurrence was observed in 12.1% of cases, primarily following conservative treatments. Conclusions: IOAF remains a challenging condition due to its locally aggressive nature and potential for recurrence. Surgical resection remains the primary treatment modality, with en bloc resection yielding the lowest recurrence rates. Further research into molecular pathogenesis and targeted therapies is needed to optimize treatment outcomes.

Rationale: Desmoid tumors (DTs) exhibit highly variable behavior, making management challenging. Specific adenomatous polyposis coli (APC) gene mutation sites are recognized as key prognostic markers, potentially enabling genotype-guided strategies to avoid overtreatment.

Patient concerns: We present 2 symptomatic patients with familial adenomatous polyposis-associated mesenteric DTs. Patient 1 was a 46-year-old female with a large, symptomatic pelvic mass. Patient 2 was a 26-year-old male with multifocal recurrent disease, including a symptomatic abdominal wall lesion.

Diagnoses: Diagnosis was confirmed by imaging and histopathology. Genetic sequencing identified intermediate-region APC mutations: a somatic c.1821T > A (p.Cys607Ter) mutation in patient 1 and a c.3183_3187delACAAA (p.Gln1062Ter) mutation in patient 2.

Interventions: Management was stratified by genotype. Given the indolent-predicting mutations, patient 1 was managed with active surveillance alone. For patient 2, the symptomatic abdominal wall lesion was resected, and low-intensity systemic therapy (tamoxifen and celecoxib) was initiated for residual mesenteric disease.

Outcomes: At 5-year follow-up, patient 1’s tumor showed >50% volume reduction with symptom alleviation. Patient 2 achieved sustained disease stability in all lesions at 3-year follow-up, with partial symptom remission. No significant treatment-related adverse events occurred.

Lessons: Intermediate-region APC mutations (e.g., codons 607 and 1062) predict an indolent course in mesenteric DTs. Comprehensive APC genotyping at diagnosis enables risk-adapted management, permitting safe use of conservative strategies (active surveillance/low-intensity therapy) and helps avoid unnecessary aggressive interventions. This underscores the critical role of molecular profiling in personalizing DT care.

Purpose: To evaluate the efficacy and safety of pegylated liposomal doxorubicin (PLD) in the treatment of desmoid tumors (DTs).

Patients and methods: In this investigator-initiated, double-blind, phase 3 trial, we randomly assigned (in a 2:1 ratio) patients with advanced or refractory DTs to receive either PLD (50 mg/m² intravenously) or placebo every 4 weeks for 6 cycles. Crossover from placebo to PLD was permitted upon disease progression. The primary endpoint was progression-free survival (PFS). The secondary endpoints were objective response and safety.

Results: From November 2020 to March 2023, a total of 73 patients were assigned to receive PLD (49 patients) or placebo (24 patients). With a median follow-up of 16.1 months, PLD had a significantly longer PFS over placebo (not reached vs. 4.3 months), with a hazard ratio (HR) of 0.05 (95% CI, 0.01-0.17; P<0.001). The 2-year PFS rates were 90.4% with the PLD group and 19.6% with placebo. PFS benefit favored PLD across most prespecified subgroups. The confirmed objective response was observed in 19 (40.4%) patients in the PLD group and 1 (4.3%) in the placebo group (P=0.002). Common grade 3 or higher adverse events with PLD included neutrophil count decreased (10.6%), mucositis oral (6.4%), and white-cell decreased (4.3%). Significant between-group differences in certain patient-reported toxicities were observed (P<0.05). Conclusions: PLD significantly prolonged PFS and induced durable responses than placebo, with a favorable safety profile, for patients with progressive or symptomatic desmoid tumors.

Familial adenomatous polyposis (FAP) is an autosomal dominant hereditary colorectal cancer (CRC) syndrome caused by germline pathogenic variants in the adenomatous polyposis coli (APC) gene. FAP is typically characterized by the development of hundreds to thousands of adenomatous polyps throughout the colon and rectum, with a nearly 100% chance of developing CRC if left untreated. Duodenal cancer is the second leading cause of cancer for patients with FAP; however, gastric cancer has become more prevalent in recent years with improved surveillance of the colon, rectum, and duodenum. Patients frequently develop other extracolonic manifestations including desmoid disease, which holds the highest extracolonic mortality risk, and thyroid nodules, which are more frequently associated with the cribriform morular variant of papillary thyroid cancer. Management of FAP is complex, and patients require frequent and lifelong surveillance. This review will discuss the current understanding and clinical management of FAP as well as innovations and challenges in clinical practice.

Background: Intra-abdominal desmoid tumours (IADT) can closely mimic gastrointestinal stromal tumours (GISTs), particularly in recurrence and metastases. However, differentiating these two diseases using radiological methods remains challenging. This study aimed to investigate the value of [18F]FAPI-42 PET/CT in differentiating IADT and GISTs compared to [18F]FDG PET/CT.

Methods: This study retrospectively included a total of 24 patients (12 patients with IADT and 12 patients with recurrent/metastatic GISTs) who underwent two separate PET/CT scans using [18F]FAPI-42 and [18F]FDG, respectively. The differences in tumour SUVmax on [18F]FAPI-42 PET/CT (SUVmax-FAPI) and [18F]FDG PET/CT (SUVmax-FDG) and the ratio of tumour SUVmax on FAPI PET/CT to SUVmax on FDG PET/CT [SUVmax ratio (FAPI/FDG)] were compared between IADT and GISTs. Receiver operating characteristic (ROC) curve analyses were performed to evaluate the diagnostic performance of these parameters in differentiating IADTs from GISTs. Immunohistochemistry was used to verify FAP expression in all IADT lesions and GISTs lesions.

Results: The SUVmax of IADTs on [18F]FAPI-42 PET/CT was significantly higher than that of GISTs [8.8 (7.2, 10.6) vs. 3.9 (2.8, 7.6), P = 0.045], whereas the SUVmax of IADTs on [18F]FDG PET/CT was significantly lower than that of GISTs [2.5 (1.9, 3.5) vs. 6.1 (3.6, 8.3), P = 0.007]. The SUVmax ratio (FAPI/FDG) of IADTs was significantly higher than that of GISTs [3.3 (2.2, 4.1) vs. 0.8 (0.3, 1.4), P < 0.001]. SUVmax-FAPI, SUVmax-FDG, and the SUVmax ratio (FAPI/FDG) achieved AUCs of 0.743, 0.819, and 0.896, with corresponding accuracies of 75.0%, 83.3%, and 87.5%, respectively, for distinguishing IADT from GISTs. Immunohistochemistry revealed significantly higher FAP expression in IADTs compared to GISTs (P = 0.002), with most IADTs showing strong (3+) staining (8/12, 66.7%), while GISTs primarily demonstrated weak (1+) or no staining (7/12, 58.3%). Conclusion: The distinct uptake characteristics of [18F]FAPI-42 and [18F]FDG observed in IADTs and GISTs provide preliminary evidence that these two tracers may offer complementary diagnostic information when evaluating desmoid tumours that mimic recurrent or metastatic GISTs.