Introduction:

Desmoid tumors are benign tumors of mesenchymal origin with a complex course of the disease, due to absence of a capsule, infiltrative growth, heterogeneous structure and shape, the true extent of which is difficult to assess before surgery [1]. The incidence of desmoid tumors is 5-6 people per 1 million population per year, mainly at the age of 30-40 years and represents 0.03% of all neoplasia [2-4]. Most often they occur in women and the ratio is 2:1-5:1 [5]. Based on etiology and anatomical location, they are classified into abdominal, intra-abdominal, extra-abdominal, multiple familial, and associated with Gardner or Turcot syndrome [3, 6].

Despite the fact that desmoid tumors are benign, WHO classifies them as intermediate locally aggressive neoplasia [7]. Wide excision remains one of the most commonly used methods of surgical treatment, with recurrence occurring in 25-50% of cases [8]. In recent years, active surveillance, antihormonal and anti-inflammatory therapy, antitumor drug therapy and radiotherapy have been alternative methods [6].

This article presents a rare case of surgical treatment of a patient with a large symptomatic desmoid tumor followed by reconstruction of the anterior abdominal wall.

Case Report

Patient R., 24 years old, in 2019, found a mass on the anterior abdominal wall. During the observation period, there was a significant increase in size, and therefore in December 2021 the patient consulted a surgeon. In the projection of the left rectus abdominis muscle, there was an oval-shaped mass with clear, even contours measuring 12x7 cm, the skin over the mass was not changed. On palpation the mass was painless, not displaceable in relation to the surrounding tissues. The patient underwent CT scan of the abdominal organs with IV contrast, which revealed a mass within the left rectus muscle with dimensions of 125 x 78 x 25 mm (Fig. 1A). We performed a core-needle biopsy of the mass. Histological examination described the mass as being composed of fragments of muscle, vascularized fibro-adipose tissue with no signs of tumor growth.

Fig. 1: A. CT picture of the tumor before surgery (the tumor is marked with an arrow). B. MRI picture after extirpation of the rectus abdominis muscle and reconstruction after 1 year (the arrow indicates the area of the removed rectus abdominis muscle).

We decided to perform a wide excision of the tumor of the anterior abdominal wall. The patient received antibiotic prophylaxis with 1 g of cefotaxime intravenously 30 minutes before surgery. Surgery was performed under combined endotracheal anesthesia. After preparation of the skin with an antiseptic solution, a midline skin incision was made along the linea alba. We visualized a dense, immobile tumor measuring 11x5 cm, intimately adhering to the subcutaneous fat and skin with invasion into the left rectus abdominis muscle. Further revision revealed tumor invasion into the posterior leaf of the rectus aponeurosis. The left rectus muscle was exposed in a blunt and sharp way, the muscle was extirpated using a bipolar coagulator, then the posterior leaf of the rectus aponeurosis with the underlying peritoneum was excised. The abdominal cavity was sutured tightly with a continuous suture. Then we performed anterior abdominal wall reconstruction with local tissues and a polypropylene implant (Fig. 2 A, B, C). In the bed of the removed rectus muscle, a silicone vacuum drainage was installed, brought out through the counter-opening in the left mesogastric region. The wound was sutured in layers with a cosmetic suture. In the postoperative period the patient required only symptomatic therapy with NSAIDs (ketorolac 30 mg IM). On the 2nd day after the operation, the drainage was removed. During control ultrasound on the 3rd day after the operation there was soft tissue edema in the area of intervention with no fluid accumulations. The patient was discharged from the hospital on the 5th day after the operation. Histological examination revealed a growth of a mesenchymal spindle cell tumor is in the dermis, subcutaneous fat and striated muscle tissue. On immunohistochemical examination, tumor cells express Beta-Catenin+/Calretinin+/SMA+/S100-, Ki-67 2%. According to the results of morphological and immunohistochemical studies, the tumor was classified as desmoid fibromatosis.

There was no recurrence at the control MRI of the soft tissues of the anterior abdominal wall after 6 and 12 months (Fig. 1B).

Fig. 2: Intraoperative picture and postoperative specimen. A - Intraoperative picture after resection of the rectus abdominis muscle, B - intraoperative picture after the installation of a mesh implant, C - resected rectus abdominis muscle with a tumor.

Discussion

In recent years, the treatment tactics of patients with desmoid tumors have undergone a number of changes. Due to the rarity and versatility of this category of patients, treatment should take place in multidisciplinary hospitals with extensive experience in the treatment of connective tissue diseases. Taking into account the unclear role of surgical treatment in patients with desmoid tumors, current recommendations indicate that they should be actively followed up and treatment may be offered as a second step [6]. In the case of an increase in the tumor, the appearance of symptoms, patients may undergo surgical treatment, mainly for single tumors localized within the abdominal wall [6]. The primary goal of surgical treatment is complete excision of a neoplasm with a negative surgical margin (R0). Incomplete excision is an important negative prognostic factor. Despite this, according to current clinical guidelines, major surgical interventions are not performed due to the risks of disability [4].

Another difficulty in the surgical treatment of desmoid tumors is the method of surgical intervention, which often results in large tissue defect. Mesh implants can be used to strengthen the anterior abdominal wall, but there is no consensus on methods of reconstruction [8]. In most cases, the on-lay technique with one or two layers of mesh implants can be performed. In this case, complications can occur in up to 42% of cases. The most common complications include postoperative wound infections, fistula formation, evisceration etc. [9]. Given the size of the mass, primary closure of the surgical wound without mesh implants is usually possible in about 10% of patients. In 85% of cases, strengthening of the abdominal wall is required to prevent postoperative hernia and evisceration [10, 11].

Systemic therapy can be used predominantly for desmoid tumors not localized within the abdominal wall, with a negative trend during active surveillance.

Radiotherapy can be used as a standalone treatment or in combination with surgical treatment if the surgical margin is positive or complete excision is not possible. Radiation load during radiotherapy should not exceed 56 Gy as higher dosages are associated with complications. The risk of recurrence with a positive surgical margin is significantly lower in the case of radiotherapy [2, 4, 6].

With the increase in the number of publications on conservative therapy in this category of patients, the role of systemic therapy has increased markedly in recent years (Table 1). It is used in case of rapid growth, when the operation is associated with damage to the vital anatomical structures or surgical treatment is not justified. At the same time, according to the accumulated experience and available clinical guidelines, the role of hormonal and anti-inflammatory therapy remains controversial. The role of chemotherapy should be assessed in terms of quality of life. It should be noted that currently the only method that has positive results is targeted therapy [4, 6].

In the presented clinical case, a number of features are observed. First of all, the patient was a male who had a rapid increase in the size of the mass, which was the reason for surgery. Given the size of the defect, in order to prevent evisceration and postoperative hernias, the abdominal wall was strengthened with a polypropylene implant. Taking into account the observation of the patient's condition in dynamics, such tactics can be justified in case of large masses with a high risk of invasion into the surrounding structures.

Conclusion

Desmoid tumors in males are rare tumors that require active monitoring, and in case of an increase or the appearance of symptoms require surgical intervention. The proposed treatment tactics in the scope of a wide excision of the formation followed by reconstruction with local tissues and a polypropylene implant is justified as it preserves oncological principles.

References

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