What is a desmoid tumor?

Desmoid tumors, also known as ligamentous tumors, are a rare type of benign hyperplasia of the aponeurosis. They occur in muscles, tendons, and deep fascia. They are very hard and histologically benign tumors, but they are locally invasive and have no capsule. They may become fibrosarcomas. Macroscopically, the tumors are irregular in shape, grayish-white in cross section, interlaced and woven, and hard like rubber. Under a microscope, the tumors are composed of abundant collagen fibers and very few fibroblasts, which are arranged in parallel. The cells have no atypia and nuclear division phases, and striated muscle islands surrounded by tumor tissue can often be seen at the edge of the tumor.

Desmoid tumors are common in people aged 30-50 years, more common in women, and can also be found in adolescents.

The cause of this disease is unknown, but it may be related to trauma, pregnancy, surgery, and systemic connective tissue abnormalities. During pregnancy, the increase in estrogen in the blood and the possible damage to the abdominal wall during childbirth may be the reason why desmoid tumors are more common in adult women.

Clinical manifestations: Those occurring in the abdominal wall present as painless abdominal wall masses that are hard, non-tender, and grow slowly. In most patients, tumors can be found when they are several centimeters in diameter. If treatment is delayed, the tumor grows to infiltrate the surrounding pieces, causing great rigidity of the abdominal wall, and other parts of the abdominal wall. This may lead to corresponding compression symptoms and functional impairment.

Diagnosis and differential diagnosis of desmoid tumors

Due to the atypical clinical and imaging manifestations of desmoid tumors, preoperative diagnosis is difficult. Desmoid tumors occurring in the abdominal wall have certain characteristics. Benign abdominal tumors are common in desmoid tumors, neurofibromas, and lipomas. Malignant tumors are lymphomas, soft tissue sarcomas, and metastatic tumors.. Lipoma CT manifestations are typical and do not require differentiation, but MRI can be used to distinguish between desmoid tumors and neurofibromas. Although desmoid tumors are locally invasive, most of them appear as soft tissue masses with clear boundaries on CT. Unlike typical malignant tumors that grow in an infiltrative manner, they can be distinguished based on clinical manifestations.