Intramuscular desmoid tumor of the leg leading to external popliteal sciatic neuropathy: A case study and literature review

Introduction and importance: Desmoid tumors (DT), rare benign neoplasms of soft tissues, exhibit local aggressiveness and high recurrence rates. Originating from myofibroblast proliferation, complete surgical intervention is the preferred treatment. Despite their benign nature, these tumors are infrequent, predominantly affecting women between 15 and 60, with a higher incidence in adolescence.

Case presentation: A 44-year-old woman with a DT in the leg mimicking external popliteal sciatic neuropathy. Diagnosis confirmed by biopsy, surgery performed with preservation of the external popliteal nerve, ensuring optimal nerve function. Two-year follow-up with no recurrence, demonstrating the success of the surgical intervention.

Clinical discussion: DTs, although rare, exhibit three distinct genomic mutations, with the 45F genotype associated with the highest risk of recurrence. Generally sporadic, these tumors can be linked to familial adenomatous polyposis (FAP) and influenced by states of hyperestrogenism. DTs typically present as deep-seated masses, with frequent local recurrence despite complete resection.

Conclusion: DTs pose diagnostic and therapeutic challenges, often requiring complete surgical intervention. Management depends on symptomatology, with careful monitoring for small asymptomatic tumors and adjuvant radiotherapy in case of incomplete resection. Despite surgical success, frequent recurrence underscores the need for in-depth research to enhance therapeutic approaches.

Desmoid tumors are soft tissue neoplasms arising from fascial and muscle-aponeurotic structure. These tumors are locally aggressive and have a high recurrence rate, even after complete resection. We present the case of a female with a giant intrathoracic desmoid tumor. She underwent complete surgical resection with no disease recurrence. Desmoid tumors’ natural history is not well defined and is often enigmatic, making these tumors difficult to manage. Currently, for intrathoracic desmoid tumors, medical treatment is the recommended approach, nevertheless, surgery can be considered in selected patients.

Purpose: To determine to the activity and safety of TGF-β inhibitor, vactosertib in combination with imatinib in patients with desmoid tumors.

Patients and methods: In this investigator-initiated, open-label, multicenter, phase Ib/II trial, patients with desmoid tumors not amendable to locoregional therapies (surgery and/or radiotherapy) or with disease progression following at least one treatment were enrolled. Participants were administered 400 mg imatinib daily in combination with vactosertib (5 days on and 2 days off, twice a day) every 28 days. In phase Ib, the vactosertib dose was set at 100 mg (level -1) and 200 mg (level 1) to determine the recommended phase II dose (RP2D). Phase II assessed the efficacy, with the primary endpoint being progression-free rate (PFR) at 16 weeks.

Results: No dose-limiting toxicities were observed during the phase Ib, therefore RP2D was defined at doses of 400 mg imatinib daily in combination with 200 mg vactosertib. Of the 27 patients evaluated, 7 (25.9%) achieved a confirmed partial response and 19 (70.4%) were stable. The PFR at 16 weeks and 1 year were 96.3% and 81.0%, respectively. The most toxicities were mild to moderate myalgia (n=10, 37%), anemia (n=10, 37%), and nausea (n=9, 33.3%). Common grade 3-4 toxicities included neutropenia (n=6, 22.2%) and anemia (n=5, 18.5%).

Conclusions: Vactosertib and imatinib combination was well-tolerated, with promising clinical activity in patients with progressive, locally advanced desmoid tumors. This is the first study investigating a novel target agent, a TGF-β inhibitor, in this rare and difficult-to-treat desmoid tumor.

Nirogacestat (OGSIVEO™) is an oral, selective, reversible, small molecule γ-secretase inhibitor developed by SpringWorks Therapeutics, Inc. γ-Secretase is a multi-subunit protease complex that cleaves multiple transmembrane protein complexes, including Notch and membrane-bound B-cell maturation antigen (BCMA). Inhibition of γ-secretase may result in growth inhibition of tumour cells overexpressing Notch, and preservation of membrane-bound BCMA may increase target density for BCMA-targeted therapy. In November 2023, nirogacestat was approved in the USA for use in adult patients with progressing desmoid tumours who require systemic treatment. This article summarizes the milestones in the development of nirogacestat leading to this first approval for the systemic treatment of desmoid tumours.

Fibromatosis is a rare locally aggressive benign tumour which arises from the musculoaponeurotic structures throughout the body. In the oral and maxillofacial region, It has been described under a variety of synonyms, including ‘extra articular desmoids’, ‘desmoids tumours’, ‘grade-1 fibrosarcomas’,’non metastasizing fibrosarcoma’and ‘aggressive fibromatosis’. The pecularity of this entity in paranasal sinuses is that it is rare in this location and are locally aggressive with higher rates of recurrence in a relatively restricted area.The purpose of this study is to present a rare case report and reviewing the literature of this entity.