Desmoid tumor of abdominal wall

Abdominal wall fibroma Abdominal wall fibromas (desmoidofabdominalwall) is a fibroid that occurs in the abdominal wall muscle layer and fascia sheath, so it is also called abdominal wall ligament-like fibroma, banded tumor, fibromatosis, because the tumor growth is invasive, easy to relapse And local destructive, also known as invasive fibromatosis, fibrous histioma-like hyperplasia, abdominal wall recurrent fibroids and abdominal fibroids. The tumor has no malignant signs in histomorphology, no lymphatic and blood metastasis, but it is invasive, recurring and locally destructive. It is different from benign and malignant tumors, so Wills (1950) defined it as Borderline tumors are recognized by more and more scholars. WHO (1994) defines it as a differentiated fibroblastic tumor with biological characteristics between benign fibroblastoma and fibrosarcoma, which can recur spontaneously without metastasis. basic knowledge The proportion of sickness: 0.002% - 0.006% Susceptible people: more common in women 30 to 50 years old with a history of pregnancy Mode of infection: non-infectious Complications: intestinal obstruction

Abdominal wall fibroma cause

(1) Causes of the disease

The cause of the disease is not well understood and may be related to the following factors.

1. Abdominal wall injury Most scholars at home and abroad believe that abdominal wall injury is one of the main factors leading to this disease. The authors have statistics of 175 cases of abdominal fibroids in 5 groups in China, including 152 cases (86.9%) of pregnancy and childbirth history. There were 35 cases (24.8%) with history of surgery and injury. The mechanism of abdominal fibrosis caused by abdominal wall injury is unclear. It may be related to abnormal destruction of muscle fiber, local hemorrhage and hematoma repair. Some scholars believe that it is caused by muscle fiber damage. The autoimmune response is related, but the injury factors can not explain the cause of abdominal fibroma in patients with men, no pregnancy, no history of surgery or trauma, and common causes of abdominal wall injury are:

(1) Surgery: Surgical treatment directly cuts the abdominal wall muscle or separates and pulls to cause muscle tearing.

(2) Abdominal blunt trauma: causing muscle fiber destruction, local bleeding or hematoma formation.

(3) Pregnancy: Chronic injury to the abdominal wall can be caused by excessive stretching of the abdominal muscles for a long time. The abdominal muscles continue to contract violently during labor, which can cause muscle fiber destruction, fracture and muscle fiber bleeding.

2. Endocrine Disorders Clinical observations and experiments in recent years have shown that this disease may be related to female hormone imbalance, based on:

(1) The disease is more common in women between the ages of 18 and 36 years old, often occurs several years after childbirth, and there are fewer cases after menopause.

(2) After the disease is castrated by ovarian radiation or enters the menopause, the tumor gradually disappears on its own.

(3) The treatment of estrogen receptor antagonists (such as tamoxifen) in a few cases has a certain effect.

(4) Animal experiments have shown that estrogen can induce the formation of this tumor. Brasfield et al. injected estrogen multiple times in the abdominal muscle layer of the white rabbit, which resulted in the occurrence of abdominal fibromas in the test animal. Application of testosterone, progesterone can be used. Inhibit the development of tumors.

(5) Estrogen receptors can be detected in specimens of hard fibroids.

3. Genetic factors As early as 1923, Nichols found that patients with familial adenomatoid polyposis were susceptible to hard fibroids. Hizawa et al reported that among the 49 patients diagnosed with familial adenomatous polyposis, 6 Cases diagnosed with invasive fibromatosis, and other statistical results show that the incidence of dural fibroma in familial adenomatoid polyposis patients is as high as 8% to 38%, 8 to 52 times higher than the normal population, given that this disease is often accompanied by Familial adenomatous polyposis, and from the neonatal period can be onset or siblings with the disease, some scholars have suggested that the incidence of dural fibroma may be related to heredity.

In recent years, scholars at home and abroad have found that in some sporadic and fibroblasts associated with familial adenomatoid polyposis, 5q deletion of APC gene and abnormal mutation of exon 15 can be detected in tumor tissue. It is known that the APC gene regulates the expression of B-chain protein, while the latter is a member of the protein membrane with adhesion and binding function, and acts as an intermediary of Wingless signaling in the nucleus to bind to transcription factors, activate gene transcription, and WntAPC--chain protein pathway The mutation of the two mediators showed that the stability of -chain protein plays a key role in the pathogenesis of scaboma. It was found that the APC gene was cleaved and a 337 base pair AluI sequence was inserted into its 1526 codon to make a mutation. And increase the level of -chain protein in the fibroblastoma cells, which is helpful for the proliferation of the fibroblastoma cells. Other experiments have shown that although the fibroma cells contain high levels of -chain protein, the expression level of the -chain mRNA is normal. The same as the surrounding normal tissue, suggesting that the degradation rate of -chain protein in the tumor tissue is lower than that of normal tissues, and it is also one of the important factors for the high level of -chain protein. Studies have shown that the deletion and mutation of APC gene, the high level of -chain protein expression and the low degradation rate of -chain protein in tumor tissue and its important role in the activation of transcription factors, lead to or promote the disease It plays an important role in the development.

In addition, by in situ hybridization and immunofluorescence, it was found that there is a high expression of C-sis gene in the fibroma cells, which promotes the production of platelet-derived growth factor R, while platelet-derived growth factor R promotes hard The mitosis of fibromatous cells and their surrounding fibroblasts.

(two) pathogenesis

Histopathology showed that the size of the fibroids was different, there was no capsule, the edges were irregular, and the surrounding tissues were infiltrating and the boundary was unclear. It was often a "lobulated" shaped mass, and the cut surface was tough as rubber, grayish white, fiber. The bundles are arranged in a braided cord, invading the surrounding tissues (such as muscles and fat), and the invaded muscles may be atrophied and degenerated. The tumor tissue can infiltrate the blood vessels, nerves and destroy these tissues, and occasionally the evil becomes a low-grade fibrosarcoma.

Microscopically, the tumor is composed of well-differentiated fibroblast proliferation and collagen fibers. The fibroblasts and fibers are often wavy and staggered. Collagen fibers are interspersed between cells, and different tumors or cells of different regions of the same tumor. The ratio of fiber to fiber is very different. Some fibers are less and more collagen. Some cells are more and less collagen, but the amount is more than that of well-differentiated fibrosarcoma. The proliferating fibroblasts are more hypertrophic, lightly stained, and the boundary is clear. Arranged, no atypical; the nucleus is long, the chromatin is spotted, with small nucleoli, visible mitotic figures, but no pathological mitotic figures (Figure 1).

In some cases, the adhesion of the tumor tissue to the surrounding muscle tissue is observed. Some cells are more active in growth, some are glassy, some are invasive growth between fat and muscle, and the muscle fiber tissue is divided into small islands, causing atrophy and degeneration. And can see multinucleated muscle giant cells.

Abdominal wall fibroma prevention

Abdominal wall fibroids do not metastasize, but are prone to recurrence. It is reported that the recurrence rate can be as high as 50% to 66.8%, and mainly in the age of 18 to 30 years old, Plukker et al believe that tumor recurrence and surgical resection range and tumor size Relatedly, the larger the tumor, the more likely it is to relapse. The case of tumors larger than 10cm has the highest recurrence rate. A few abdominal wall fibroids can exist for a long time without excessive surgical resection, but some scholars have reported repeated recurrences. Surgery may result in tumor metastasis.

The tumor has the possibility of self-resolving, and even some large abdominal fibroids can naturally retreat or disappear without any treatment.

Abdominal wall fibroma complications Complications, intestinal obstruction

Abdominal wall fibroma is invasive, and may cause incomplete intestinal obstruction or bladder irritation when it invades the abdominal lumen or bladder.

Abdominal wall fibroma symptoms common symptoms slow growth abdominal pain colon polyps abdominal wall erythema

The disease can occur from the newborn to the elderly, but women with a history of pregnancy from 30 to 50 years old and those with a history of abdominal surgery or abdominal wall trauma are more common. They can be seen in any part of the abdominal wall, especially below the abdomen, trauma and the original. Surgical incisions and adjacent areas are prone to occur.

1. Symptoms of abdominal wall ligament-like fibroids grow slowly, with a long course of disease and no obvious symptoms, a few with local pain or occasional discomfort, often found as an abdominal wall mass, due to the growth of abdominal wall ligament-like fibroids The limitation of muscle and fascia, the long diameter of the tumor is more than 5cm, and the ligament-like fibroma of other parts outside the abdominal wall can grow into a huge mass due to the absence of the above anatomical features. The tumor growth of women in childbearing age is faster. The growth rate of tumors before and after menopause.

2. The sign is a hard mass of the abdominal wall. The boundary is often not clear. It is consistent with the direction of the abdominal muscle fibers. When the abdominal wall muscle contracts, the mass is fixed and cannot move. After the abdominal wall muscle relaxes, the tumor can be pushed along the abdominal wall.

The advanced tumor grows in a sheet-like infiltration and develops into a large abdominal wall of hard fibroma, which can cause large abdominal wall stiffness.

Abdominal wall fibroma examination

1.B ultrasound images are characterized by relatively regular morphology, clear borders, low echo or echogenic masses inside, echo enhancement during degeneration and necrosis, and generally no blood flow in the tumor. This examination can determine the location of the tumor in the abdominal wall tissue and The extent of infiltration helps to eliminate intra-abdominal masses.

2. CT scan of hard fibroma on CT is mostly a soft tissue mass with clear boundary and uniform density, but the boundary is often unclear when the lesion is small. When the lesion is large, a group of muscles have been "eating" by the tumor, surrounded by subcutaneous fat phase. The multi-display boundary is clear, the tumor is flat and uniform, and the enhanced scan can better show the tumor boundary. The boundary is extremely irregular and infiltrating. The tumor is claw-like and eats normal muscle.

Compared with muscle when enhancing the scan: when the tumor is large, the lesion density is slightly higher or the muscle density is trabecular, and the strip or eccentric large circular low density changes are scattered, trabecular or strip-like The muscle fibers are in the same direction; if the tumor is small, histology shows that there is still a certain amount of normal muscle tissue between the tumor tissues, but it is not enough to be expressed on the image, so the CT scan shows uniform uniform density or slightly high density, and there are few reports in the literature. Hard fibroma can be seen as calcification, cartilage or ossification, but some scholars believe that the abdominal wall of hard fibroma is small, the flat and enhanced more uniform uniform density, only the local muscles are slightly swollen, the fat gap is blurred; due to the abdominal wall muscle Signs of small and thin, claw-like infiltration and multiple low-density changes in the eccentricity of the tumor are often not manifested and must be combined with clinical considerations.

3. Compared with CT, MRI can more accurately show the location, extent and morphology of the lesion, the claw-like infiltration at the edge of the lesion, and whether there is an envelope, which can clearly show whether there is adipose tissue in the lesion. There is an edema area around the lesion. The abdominal fibromatosis is mainly composed of bundled intertwined fustal fibroblasts and unequal amount of dense collagen tissue. In different cases, different parts of the same lesion, fusiform fibroblasts and collagenous tissue. The ratio of MRI multiple sequence scanning can truly reflect the histological composition of the lesion. The signal can be changed due to the difference in the proportion of fibroblasts and collagen tissue in the lesion. On the T1-weighted image, it can be a low signal compared with the muscle, and a high signal on the T2-weighted image; the lesion with the collagen component and the small cell component is slightly lower on the T1-weighted image and the T2-weighted image. In the same case, because the periphery of the lesion is mainly composed of collagen, and the central part is mainly composed of cells, the peripheral signal on the T2-weighted image is lower than the central region; invasive growth or recurrence Lesions which are often cellular components than collagen, but also of that, since the duration of the elderly shrinkage, increased collagen tumor instinct and signal reduction.

The MRI manifestations of this disease are intramuscular lesions, relatively homogeneous, no necrosis, no calcification, no fat tissue, lesions with low signal or equal signal on T1-weighted images, T2-weighted lesions are high signal, signal intensity is slightly Below the subcutaneous fat, some small low-signal areas can be seen in the lesions, which are consistent with the muscle signals, which are caused by the remaining muscle islands. After the enhancement, the lesions are obviously strengthened, while the remaining muscle islands are not enhanced.

Diagnosis and diagnosis of abdominal fibroma

Diagnostic criteria

The diagnosis of this disease is not difficult. For patients with a round or elliptical mass with a hard abdominal wall and a margin that is not clear, the following points can be confirmed.

1. History of pregnancy, history of abdominal surgery and history of abdominal trauma.

2. Have a family history of multiple colon polyposis or have Gardner syndrome.

3. There is no metastatic sign, but there are multiple recurrences after local resection.

4. The abdominal wall, especially the lower abdominal wall, has a slow-growing painless or slightly painful mass, which is elliptical or long-shaped, hard and fixed, the boundary is unclear, most of them are not tender, and the Bouchocoun sign is negative (positive can be determined as the abdominal wall) Inside the mass).

5. Invasive growth invades the intestinal lumen or bladder and produces corresponding incomplete intestinal obstruction or frequent urination, urgency and other symptoms.

6. B-ultrasound, CT or MRI showed images of space-occupying lesions and infiltrating surrounding tissues in the abdominal wall.

7. Pathological examination showed that fibroblasts proliferated in the tumor, and there were a large number of collagen matrix around fibroblasts, in which the number of cells was large, fibroblasts often invaded adjacent normal structures, fibroblasts had no atypia, and no pathological mitotic figures.

Differential diagnosis

Abdominal wall fibroma is invasive, and may cause incomplete intestinal obstruction or bladder irritation when it invades the abdominal lumen or bladder.

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