A case report of rectal schwannoma treated with laparoscopic proctectomy

Comprehensive evaluation of rare case: From diagnosis to treatment of a sigmoid Schwannoma: A case report

BACKGROUND

Schwannomas are uncommon tumors originating from Schwann cells, forming the neural sheath. They account for approximately 2%-6% of all mesenchymal tumors and are most commonly identified in peripheral nerve trunks, with rarity in the gastrointestinal tract. Among gastrointestinal locations, the stomach harbors the majority of nerve sheath tumors, while such occurrences in the sigmoid colon are exceptionally infrequent.

CASE SUMMARY

This study presented a clinical case involving a 60-year-old female patient who, during colonoscopy, was diagnosed with a submucosal lesion that was later identified as a nerve sheath tumor. The patient underwent surgical resection, and the diagnosis was confirmed through immunohistochemistry. This study highlighted an exceptionally uncommon occurrence of a nerve sheath tumor in the sigmoid colon, which was effectively managed within our department. Additionally, a comprehensive review of relevant studies was conducted.

CONCLUSION

The preoperative diagnosis of nerve sheath tumors poses challenges, as the definitive diagnosis still relies on pathology and immunohistochemistry. Although categorized as benign, these tumors have the potential to demonstrate malignant behavior. Consequently, the optimal treatment approach entails the complete surgical excision of the tumor, ensuring the absence of residual lesions at the margins.

Current status of the diagnosis and treatment of gastrointestinal schwannoma

Gastrointestinal schwannoma is a rare, slow-growing and benign tumor that mostly originates in the Auerbach myenteric nerve plexus in the gastrointestinal tract. The clinical manifestations may be associated with the location, size, differentiation type, and degree of malignancy of the tumor. Endoscopy, ultrasound and imaging examinations serve an important auxiliary role in the clinical identification, diagnosis and differential diagnosis of lesions; assessment of risk; and preparation for surgery. S-100 positivity is a hallmark of schwannoma. CD34, CD117, discovered on GIST-1, P53, ALK, β-catenin, smooth muscle actin and Desmin negativity are helpful for the identification of other gastrointestinal stromal tumors. Surgical removal of the tumor is the main treatment for schwannoma. Benign gastrointestinal schwannoma has a good prognosis without recurrence and metastasis; malignant transformation is extremely rare and has a poor prognosis.

Minimizing the surgical approach for a rare disease: transanal endoscopic microsurgery for rectal schwannoma

OBJECTIVE

Rectal schwannomas are extremely rare tumors and their surgical treatment is widely variable in literature. Transanal endoscopic microsurgery (TEM) approach could be a reasonable option for such lesions, offering an organ-sparing strategy, but evidence is scarce.

METHODS

We report a 69-year-old man with a rectal submucosal lesion at 10 cm from the anal verge, treated by TEM. A systematic literature review on surgical approaches in rectal schwannoma was performed.

RESULTS

The patient was successfully treated by TEM, with adequate excision of the submucosal lesion. Histopathology revealed a rectal schwannoma. No recurrence was found at 1-year endoscopic follow-up. Previous studies reported 23 cases of rectal schwannoma and several treatment options, but only 2 cases were treated by TEM. Anterior rectal resection was generally adopted in cases of large, symptomatic masses with inconclusive preoperative biopsy, while lesions with features suggestive of stromal tumors were preferentially treated by endoscopy or, if located in distal rectum, by transanal approaches.

CONCLUSIONS

An organ-sparing minimally invasive approach should be the standard of care for rectal schwannomas. TEM could extend the indication for their endoscopic treatment, providing adequate excision even for larger schwannomas of the middle-upper rectum.

Gastrointestinal schwannomas: a rare but important differential diagnosis of mesenchymal tumors of gastrointestinal tract

BACKGROUND

Schwannomas of gastrointestinal tract are rare, mostly benign and notably different neoplasms from conventional schwannomas that arise in soft tissue or the central nervous system. These tumors are of clinical importance since they should always be considered in the differential diagnosis of submucosal lesions of gastrointestinal tract.

METHODS

Seven patients with a pathologically proven gastrointestinal schwannoma were identified in our series of mesenchymal tumors and reviewed retrospectively. Clinicopathological and immunohistochemical parameters along with the follow-up results were analysed.

RESULTS

The series included two males and five females, with a mean age 69 years (range, 39-81). Most patients were asymptomatic on presentation, except for two patients with abdominal pain. In the other cases (n = 5), the tumor was an incidental finding during other medical, imaging or surgical procedures. The tumors were located in the stomach (n = 4) and in the small intestine (n = 3) with an average size of 29 mm (range, 12-70). A preoperative diagnosis was achieved only in one case with a CT-guided core biopsy. Otherwise the clinical, intraoperative, endoscopic or radiological findings were unspecific. Patients with gastric tumor underwent either laparoscopic (n = 2) or open (n = 2) gastric wedge resection of the tumor; in the cases of intestinal tumor (n = 3) a segmentectomy was performed. Pathological examination revealed solid homogenous tumors, which were highly cellular and composed of spindle cells with positive staining for S100 protein, and confirmed the diagnosis of schwannoma. All tumors were negative for c-Kit, smooth muscle actin, desmin and DOG-1 and showed very low proliferation index. There were negative resection margins and no malignant variants were recognized. At an average follow-up of 60 months (range, 24-185) all patients were free of disease with no signs of recurrence or metastases and acceptable gastrointestinal function.

CONCLUSIONS

Schwannomas are rare, slow-growing and mostly asymptomatic gastrointestinal mesenchymal tumors. They are difficult to be diagnosed preoperatively as endoscopic and radiological findings are nonspecific but histological and immunohistochemical features are of paramount importance to differentiate between benign and malignant schwannomas, or other spindle cell sarcomas. The treatment of choice is complete surgical excision without a conclusive preoperative diagnosis, and the long-term outcome is excellent as these lesions are mostly benign.