LEIOMYOSARCOMA OF THE RIGHT COLON: A CASE REPORT

Case Presentation A 38-year-old male patient, post-renal transplant from a living donor in 2009 due to type 1 diabetes mellitus, presented with weight loss. A colonoscopy performed on 07/27/2022 revealed a pedunculated, lobulated, and voluminous lesion covered with fibrin, approximately 50mm in diameter, occupying about 70% of the intestinal lumen. Tattooing and biopsy of the lesion were performed. The pathological result showed a fusocellular neoplasm with focal moderate atypia and a low mitotic index. The patient was then subjected to right colectomy via laparoscopy on 08/11/2022. The pathological examination was consistent with a proliferative fusocellular colon lesion, predominantly affecting the submucosa, with extension to the mucosa and ulceration of the adjacent epithelium. One mitosis per 5mm² was identified. Surgical margins were free of disease. Twenty-nine lymph nodes were examined, all without signs of involvement. Immunohistochemistry revealed preserved histone H3 and focal smooth muscle actin positivity. The patient experienced multiple perioperative and postoperative complications, including latex anaphylaxis and anastomotic fistula. He underwent further surgical treatment and later ileocolostomy closure in 2023. Since then, there has been no disease recurrence, with clinical improvement and significant weight gain.

Discussion Intestinal leiomyosarcomas are rare, accounting for approximately 0.1% of cases of malignant neoplasms in the colon. These tumors originate from the muscular layer of the intestinal wall or the muscularis mucosa. Some cases are asymptomatic, and the diagnosis is often an incidental finding during preventive screening exams. Diagnosis is based on clinical examination, supported by imaging, endoscopic evaluations, and pathology with immunohistochemistry. The recommended treatment is surgical resection of the affected intestinal segment. No established chemotherapy regimen exists due to the low incidence of the pathology and its limited impact on prognosis. The five-year survival rate for tumors smaller than 5 centimeters, without metastases, and well-differentiated is around 50%.

Conclusion Malignant tumors derived from intestinal muscle are rare, emphasizing the importance of preventive colon exams for early detection. Histological and immunohistochemical confirmation of the lesion is essential to determine the appropriate treatment, which should preferably be surgical.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
25 April 2025