Aggressive fibrous tumors (AF) are known by many different names and are customarily called ligament-like tumors. It is a rare tumor of fibrous tissue origin, accounting for 1.19% of fibrous tissue tumors. It is a rare tumor of fibrous tissue origin, accounting for 1.19% of all fibrous tissue tumors. It is pathologically benign, but clinically aggressive in growth and highly recurrent, but does not metastasize. Currently, surgery is the main treatment for this disease, and radiotherapy and hormonal therapy also have a role, but none of the results are satisfactory; therefore, there is a need to reconceptualize and evaluate this type of lesion. 1. Epidemiology The disease was first described by Mc.Farlane in 1832, and was officially named by Muller in 1838. Scholars at home and abroad have conducted in-depth studies on it and agreed that the incidence of this disease is very low, accounting for 0.03% of soft tissue tumors, but the incidence of familial adenomatous polyposis is as high as 8%-38%, which is 852 times higher than that of the general population. The etiology of adenomatous polyposis is not completely clear, but may be related to trauma, endocrine and defective growth regulation of connective tissue. In familial adenomatous polyposis, about 80%-90% of the tumors are located in the small intestine mesentery and abdominal wall, and the age is mostly 25-30 years old. Sclerofibrosarcoma is sometimes associated with pain and local swelling, especially when it invades the adjacent neurovascular and joints. The diagnosis mainly relies on pathological examination, but it is worth noting that fine needle aspiration biopsy is not very helpful due to the lack of cytologic integrity of the material taken, and MRI has a reference value. What can be seen with the naked eye:The tumor is of different sizes, without envelope, with irregular margins, tough texture like rubber, grayish-white cut surface and woven arrangement of fiber bundles, often invading surrounding tissues, such as muscle and fat inside. Microscopically, the tumor is composed of well-differentiated fibroblasts and collagen fibers. The fibroblasts are large, with long nuclei, lightly stained, and 1-3 nucleoli. The tumor cells often invade the surrounding tissues and the muscle fibers are separated into small islands and undergo atrophy and degeneration, and multinucleated muscle giant cells are seen. Ligament-like tumors arise from deep connective tissue, mainly monoclonal fibroblastic tumors of intramuscular connective tissue and its overlying fascia or tendon membrane. Among these, those of extra-abdominal origin are called extra-abdominal ligamentous tumors, which were first reported by Nichols in 1923. It is morphologically benign, but its biological behavior is low-grade malignant, with aggressive growth, easy recurrence, but no metastasis. It is also known as invasive fibromatosis, non-metastatic fibrosarcoma, and extra-abdominal wall fibromatosis. This tumor is a benign, tumor-like fibrous tissue proliferative disease originating from the tendon membrane, but not a true tumor. It is characterized by progressive local infiltration of muscle and surrounding soft tissues. The tumor is usually found on the anterior abdominal wall, rectus abdominis muscle and its tendon membrane, but also on the transverse muscle outside the abdominal wall, most commonly in women during pregnancy or postpartum, and most often in 20-40 years old. It can occur outside the abdominal wall at birth, or in infants, children or adults, but mostly under 30 years of age, with no significant gender differences. It can occur in the tendon membrane of the neck, trunk or extremities. The tumor is hard, slow-growing, without envelope, single or multiple, single is more common, size varies, diameter can be 1.5cm or larger, surface skin is normal, there are certain boundaries located in the deep subcutaneous layer or muscle, related to the tendon membrane, larger damage can occur mucus-like degeneration or cystic change, although local aggressive growth, can involve the surrounding tissues and organs, but no metastasis occurs. There are usually no conscious symptoms, but compression of adjacent nerves may produce pain or numbness. The disease may be part of Gardner’s syndrome. The etiology is unknown, and the nature of the lesion is a fibromatous proliferation of connective tissue. It may be associated with trauma, especially in the abdomen of postpartum women, or with scarring of the abdominal wall after surgery, causing an over-reactive proliferation of fibrous tissue. Lever suggests that this tumor occurs mainly in the muscle and tends to invade the surrounding tissue, independent of trauma. It is also thought to be associated with hormonal abnormalities. Pathogenesis: The nature of the lesion is fibromatous proliferation of connective tissue. It may be associated with trauma, especially in the abdomen of postpartum women, or on the scar of the abdominal wall after surgery, causing an overreaction of the fibrous tissue to proliferate. Lever suggests that this tumor occurs mainly in the muscle and tends to invade the surrounding tissue, independent of trauma. It is also thought to be associated with hormonal abnormalities. Pathologic changes: This tumor is non-encapsulated, hard, grayish-white, fibrous, and often invades muscle. Microscopically, the tumor is composed of abundant collagen fibers and many fibroblasts, with collagen bundles arranged in parallel or interlaced, and ovoid or spindle-shaped nuclei without heterogeneous or atypical nuclear divisions. Fibrous tissue invades the muscle bundle and can encircle and insert into the muscle bundle, leading to muscle degeneration or necrosis, or even destroying it. The nuclei of the degenerated muscle fibers are heteromorphic or regenerate and appear as multinucleated myoblasts. Rarely, iron-containing heme is seen. Areas of mucinous degeneration, even cystic, and calcified areas are seen within the tumor. The diagnosis is not difficult to determine based on the clinical site of onset in relation to the tendon and the pathological changes and other features, which need to be distinguished from keloid in clinical practice. Because of its infiltrative growth, it should be distinguished from well-differentiated fibrosarcoma, which is generally faster growing, often with pseudo-envelope, soft texture, and mostly with necrotic foci, richer tumor cells, more obvious heterotypes, and more frequent nuclear mitotic signs. (1) Surgery Surgery has been the first line of treatment for AF patients, even though sometimes surgery may affect the beauty and function of the affected area, the side effects of surgery may seem insignificant compared to the organismal harm caused by AF. The main factor affecting the prognosis is the incision margin. The general surgical principle is to try to achieve a negative margin of 1-5 cm in order to safeguard the function and avoid recurrence. Nuyttens et al. also showed that a combination of surgery and radiation therapy resulted in a significant increase in the cure rate, regardless of whether the margin was negative or positive. Many studies have reported risk factors for local recurrence, including tumor diameter greater than 4 cm, inadequate margins, age at presentation less than 32 years, and extra-abdominal AF. Most of the reports support the treatment plan of surgery plus radiotherapy. (2) Radiotherapy for AF is mainly applied to patients with unresectable, incompletely resected or positive margins, and Ewing suggested as early as 1928 that the response of sclerofibrosarcoma to radiotherapy is “slow but effective”. Many recent studies have also shown definite therapeutic effects of radiotherapy alone and adjuvant radiotherapy after surgery. The University of Florida College of Medicine achieved excellent results in 65 patients treated with AF radiation therapy, and additional surgery did not significantly improve their outcomes. Regardless of the treatment, primary DT is generally more effective than recurrent DT. radiotherapy does not reduce the recurrence rate, but prolongs the time to recurrence. Analysis has shown that there is no significant difference between radiation therapy doses of 50-60 Gy and doses above 60 Gy, while side effects increase significantly at doses above 60 Gy, especially in patients who have undergone osteotomy, bone scraping or other procedures that affect lymphatic flow. The side effects include slow tissue growth, fibrosis, edema, skin ulcers, cellulitis, pathological fractures, secondary tumors, and neurological lesions including paresthesia and sensory abnormalities. (3) Chemotherapy As familial adenomatous polyposis (FAP), patients have a 3.5%-32% incidence of AF, and surgery is mostly powerless for this, which makes drug therapy even more important. Currently, NSAIDs and anti-estrogen drugs are the first line of treatment, while cytotoxic chemotherapeutic agents are used when surgery, radiotherapy and NSAIDs and anti-estrogen drugs are ineffective. NSAIDs have been shown to reduce the number of polyps in the GI tract of patients with FAP, and it is inferred that they should also be effective in DT, which has the same pathogenesis. The most used NSAID for the treatment of DT is sulforaphane, but there are no large randomized studies on its efficacy. Given the observation that premenopausal women have a higher incidence of DT than postmenopausal women, as well as men, and that their DT is more aggressive, anti-estrogenic drugs have become one of the mainstays of current DT therapy. Raloxifene and tamoxifen are more frequently used, and other drugs such as cAMP inhibitors, alpha interferon, and the antifibrotic drug pirfenidone have been used, but all of them lack bulk randomized studies. ① chemotherapy is effective in AF; ② small doses of vincristine and methotrexate chemotherapy have been effective and clinically beneficial, but increasing the dose of chemotherapy drugs may not increase the efficacy of AF chemotherapy; ③ preoperative induction chemoradiotherapy may increase the surgical resection rate of AF patients, but may have little effect on the recurrence rate; ④ other treatments, such as gene therapy and monotherapy, have yet to be validated over time.