Biclonal Desmoid-Type Fibromatosis With Two Beta-Catenin Mutations: Evidence for the Recruitment of Normal Myofibroblasts

Sporadic aggressive fibromatosis, or desmoid-type fibromatosis, is characterized by oncogenic mutations in CTNNB1. The clonal cell is a myofibroblast-like cell, and it has been hypothesized that the recruitment of normal myofibroblasts could contribute significantly to the tumor. We describe a case in which a CTNNB1 p.T41A mutation was present at a mutant allele frequency of 30%, suggesting that a significant proportion of the tumor myofibroblasts may have been recruited from normal precursor pools. In addition, a small subclone with a p.S45F mutation (allele frequency of 2%) was identified in the tumor. This case provides additional evidence that myofibroblasts recruited by a tumor from a normal precursor pool contribute significantly to the tumor; such recruitment could impact response to treatment and long-term outcomes.

Background: There are lacking standard treatment guidelines for aggressive fibromatosis (AF) because of its rarity. Aim: This study aimed to investigate the risk factors for recurrence and survival of abdominal AF after radical surgical resection. Methods: From August 2012 to December 2020, a retrospective analysis was conducted on the clinical data of 69 AF in Shanghai Public Health Clinical Center Affiliated to Fudan University, with the tumor locating either in the abdominal wall or in the abdominal cavity. The main observation end point was progression-free survival time (PFS) and overall survival time (OS). Results: All 69 patients achieved microscopic R0 resection, 10 (14.5%) had local recurrence, and 3 (4.3%) died. The PFS rate after 1, 3, 5, and 10 years was 96.8%, 87.7%, 78.8%, and 78.8%, respectively. The OS rate after 1, 3, 5, and 10 years was 100%, 100%, 92.9%, and 81.3%, respectively. In 10 patients with recurrence, the median recurrence time was 17.6 months. Concomitant familial adenomatous polyposis (FAP) and history of previous recurrence were independent risk factors of post-operative recurrence. Conclusion: After radical surgery of abdominal AF, the local recurrence rate was 15%. Concomitant FAP and a previous history of recurrence were independent risk factors of post-operative recurrence. R0 and a combined organ resection should be performed especially in FAP patients to minimize the recurrence and improve the prognosis. Relevance for patients: The present study identifies the risk factors of recurrence in AF and suggests R0 resection especially in concomitant FAP patients. A wait-and-see strategy should not be generally implemented and radical surgery will bring clinical benefits to patients with such kind of rare disease.

To assess the efficacy and safety of ultrasound (US)-guided high-intensity focused ultrasound (HIFU) ablation for treatment of unresectable and recurrent intra-abdominal desmoid tumors. From June 2014 to March 2020, 15 patients with consecutive unresectable and recurrent diseases that pathologically proven to be intra-abdominal desmoid tumors had undergone the treatment of US-guided HIFU ablation. All patients underwent contrast-enhanced magnetic resonance imaging before and after HIFU treatment. Nonperfused volume ratio was used to evaluate the effect of HIFU therapy. Intraprocedural and postprocedural adverse effects and complications are recorded to assess the safety of the therapy. Outcome of HIFU ablation has been investigated through serial contrast-enhanced imaging examinations during follow up. Out of 15 patients 14 of them have successfully completed the whole therapy, 1 patient is ineffective and gives up further treatment. The mean nonperfused volume ratio is 71.1% (95% confidence interval, 3% to 88.2%). During a mean follow up of 29 months (range from 8 to 61 months), the mean tumor volume was reduced by 59% (95% confidence interval, +49% to -100%). No tumor spreads along the treated area in all patients except one. Complications have occurred in 5 patients (33.3%), including bowel rupture (1 case), intra-abdominal abscess (1 case), slight injury to the femoral nerve (1 case), and bone injury (2 cases), the bowel rupture patient underwent surgery; the others have been cured during the follow up. US-guided HIFU ablation is an effective treatment modality for patients suffered from unresectable and recurrent intra-abdominal desmoid tumors.

Background: Desmoid tumors are rare lesions. Although they demonstrate tumor characteristics, such as infiltrative growth and tendency towards local recurrence, they lack the ability to metastasize. To date, the cause of desmoid tumors is unknown. They can occur in both sexes, but predominant slightly in women, including nulliparous women, of reproductive age, but mostly during and after pregnancy. Case presentation: A 36-year-old nulliparous Nigerian woman presented with a large desmoid tumor of the anterior abdominal wall, mimicking recurrent leiomyoma. At presentation, she had a painless abdominal mass for 1 year, which was first noticeable as a small induration that progressively increased in size. The patient had a previous surgical history of open myomectomy for symptomatic fibroids of 3 years duration, prior to presentation. Treatment comprised a complete excision of the tumor with a wide margin and partial omentectomy and the anterior abdominal wall closed in layers, though without prosthesis. The patient subsequently developed incisional hernia. Conclusions: Large desmoid tumors may be misdiagnosed or mistaken for uterine leiomyoma or other abdominal or pelvic tumors. Attention should therefore be paid to detailed patient history and systematic clinical evaluation. To guard against incisional hernia associated with surgical resection of huge desmoid tumors, mesh reconstruction is recommended.

Desmoid fibromatosis is a rare disease caused by genetic alterations that activate β-catenin. The tumors were previously treated with aggressive surgeries but do not metastasize and may regress spontaneously. For these reasons, in the absence of symptoms and when growth would not induce significant complications, active observation is considered first-line therapy. When intervention is required, surgery can be considered based on anatomy and risk of postoperative recurrence, but increasingly nonoperative therapies such as liposomal doxorubicin or sorafenib are prescribed. Cryoablation, chemoembolization, and high-intensity focused ultrasound can also be used to obtain local control in selected patients.

Desmoid tumors (DTs) are rare locally aggressive benign soft tissue tumors with an estimated annual incidence of two to four new cases per million people. The giant intra-abdominal mass presents a diagnostic challenge that includes a broad differential diagnosis of gastrointestinal stromal tumor (GIST), fibrosarcoma, retroperitoneal fibrosis, and other malignancies from adjacent organs. We report a case of a 38-year-old male patient with a giant intra‑abdominal mass. Magnetic resonance imaging (MRI) of the abdomen and pelvis indicated mucinous cystic neoplasm or gastrointestinal stromal tumor (GIST), but histopathology confirmed it to be a desmoid tumor. The patient was discharged, and on follow-up five months until now, there is no recurrence. This case highlighted the importance of including DT in the differential diagnosis of very large intra‑abdominal masses.