Desmoid tumours (extra-abdominal), a surgeon’s nightmare

Desmoid tumours are a rare fibroblastic proliferation of monoclonal origin, arising in deep soft-tissues. Histologically, they are characterized by locally aggressive behaviour and an inability to metastasize, and clinically by a heterogeneous and unpredictable course. Desmoid tumours can occur in any anatomical site, but commonly arise in the limbs. Despite their benign nature, they can be extremely disabling and sometimes life-threatening, causing severe pain and functional limitations. Their surgical management is complex and challenging, due to uncertainties surrounding the biological and clinical behaviour, rarity, and limited available literature. Resection has been the first-line approach for patients with a desmoid tumour but, during the last few decades, a shift towards a more conservative approach has occurred, with an initial ‘wait and see’ policy. Many medical and regional forms of treatment are also available for the management of this condition, and others have recently emerged with promising results. However, many areas of controversy remain, and further studies and global collaboration are needed to obtain prospective and randomized data, in order to develop an appropriate shared stepwise approach.

Fibroblastic and myofibroblastic tumors are a variable group of neoplasms ranging from benign to malignant. These lesions may affect patients of any age group but are more frequently encountered in the pediatric population. Patient clinical presentation depends on the location, growth pattern, adjacent soft-tissue involvement, and pathologic behavior of these neoplasms. In the 2020 update to the World Health Organization (WHO) classification system, these tumors are classified on the basis of their distinct biologic behavior, histomorphologic characteristics, and molecular profiles into four tumor categories: (a) benign (eg, fibrous hamartoma of infancy, nodular fasciitis, proliferative fasciitis, fibroma of the tendon sheath, calcifying aponeurotic fibroma); (b) intermediate, locally aggressive (eg, desmoid fibromatosis); (c) intermediate, rarely metastasizing (eg, dermatofibrosarcoma protuberans, myxoinflammatory fibroblastic sarcoma, low-grade myofibroblastic sarcoma, infantile fibrosarcoma); and (d) malignant (eg, sclerosing epithelioid fibrosarcomas; low-grade fibromyxoid sarcoma; myxofibrosarcoma; fibrosarcoma, not otherwise specified). Detection of various components of solid tumors at imaging can help in prediction of the presence of corresponding histopathologic variations, thus influencing diagnosis, prognosis, and treatment planning. For example, lesions with a greater myxoid matrix or necrotic components tend to show higher signal intensity on T2-weighted MR images, whereas lesions with hypercellularity and dense internal collagen content display low signal intensity. In addition, understanding the radiologic-pathologic correlation of soft-tissue tumors can help to increase the accuracy of percutaneous biopsy and allow unnecessary interventions to be avoided.

Desmoid tumors (DT) are rare, locally aggressive, fibroblastic soft-tissue tumors that are characterized by infiltrative growth and can affect organs and adjacent structures, resulting in substantial clinical burden impacting patients’ health-related quality of life. Searches of PubMed, Embase, Cochrane, and key conferences were conducted in November 2021 and updated periodically through March 2023 to identify articles describing the burden of DT. Of 651 publications identified, 96 relevant ones were retained. Diagnosis of DT is challenging because of its morphologic heterogeneity and variable clinical presentation. Patients visit multiple healthcare providers, often facing delays in correct diagnosis. The low incidence of DT (estimated 3-5 cases per million person-years) limits disease awareness. Patients with DT experience a high symptom burden: up to 63% of patients experience chronic pain, which leads to sleep disturbance (73% of cases), irritability (46% of cases), and anxiety/depression (15% of cases). Frequently mentioned symptoms are pain, limited function and mobility, fatigue, muscle weakness, and swelling around the tumor. Overall, quality of life in patients with DT is lower than in healthy controls. There is no treatment approved by the US Food and Drug Administration for DT; however, treatment guidelines reference available options, such as active surveillance, surgery, systemic therapy, and locoregional therapy. Choice of active treatment may depend on tumor location, symptoms, and risk of morbidity. The substantial burden of illness of DT is related to difficulties in timely and accurate diagnosis, high symptom burden (pain and functional limitations), and decreased quality of life. There is a high unmet need for treatments that specifically target DT and improve quality of life.

In the United States, approximately 850-900 children and adolescents each year are diagnosed with soft tissue sarcomas (STS). STS are divided into rhabdomyosarcoma (RMS) and non-rhabdomyosarcoma STS (NRSTS). RMS and NRSTS are risk stratified into low-, intermediate-, and high-risk categories, with 5-year survival rates of approximately 90%, 50%-70%, and 20%, respectively. Recent key achievements from the Children’s Oncology Group (COG) STS Committee include the identification of new molecular prognostic factors for RMS, development and validation of a novel risk stratification system for NRSTS, successful completion of a collaborative NRSTS clinical trial with adult oncology consortia, and collaborative development of the INternational Soft Tissue SaRcoma ConsorTium (INSTRuCT). Current COG trials for RMS are prospectively evaluating a new risk stratification system that incorporates molecular findings, de-intensification of therapy for a very low-risk subgroup, and augmented therapy approaches for intermediate- and high-risk RMS. Trials for NRSTS exploring novel targets and local control modalities are in development.

Desmoid tumors are rare; however, they sometimes form in the abdominal wall after surgery or trauma. We report a case of desmoid tumors in the abdominal wall mimicking port-site metastasis after laparoscopic surgery for endometrial cancer. A 53-year-old woman with familial adenomatous polyposis presented to our hospital with vaginal bleeding and was diagnosed with endometrial cancer. We performed a total laparoscopic hysterectomy and began observation. Two years after surgery, follow-up computed tomography revealed three nodules with a size of approximately 15 mm in the abdominal wall at the trocar sites. Tumorectomy was performed because endometrial cancer recurrence was suspected, but desmoid fibromatosis was finally diagnosed. This is the first report of desmoid tumors at the trocar site after laparoscopic surgery for uterine endometrial cancer. Gynecologists should be aware of this disease because differentiating it from metastatic recurrence is challenging.

Treating pediatric desmoid fibromatosis (DF) remains a challenge due to its unpredictable nature and potential morbidity associated with aggressive treatments. A wait-and-see approach is becoming acceptable for some cases. But, clinical predictors of prognosis are uncertain, and tumor location and size do not always correlate with disease behavior. This study explored miRNA expression patterns in DF tumors to predict their clinical behavior. Five miRNAs showed potential value in predicting DF behavior, but further validation through larger multi-institutional studies and prospective clinical trials is needed. The rarity of pediatric DF poses a limitation in obtaining a substantial sample size for analysis.