Primary leiomyosarcoma of the colon: a report of two cases and review of literature.

Introduction: Primary leiomyosarcoma (LMS) of the colon is a rare neoplasm and constitutes less than 0.1% of all colon malignancies. These tumors are more aggressive and have poorer prognoses than other gastrointestinal tumors, including gastrointestinal stromal tumors (GIST) or adenocarcinomas. The authors herein report two cases and review the literature to highlight the epidemiology, diagnosis, treatment and prognosis of this uncommon malignancy. Case report: The authors reported two very rare cases of LMS of left colon, which referred to our institution with symptoms of abdominal pain. After the initial investigations, patients were diagnosed with primary colonic leiomyosarcoma that underwent laparotomy. In both cases pathological examination revealed a spindle cell tumor growing circumferentially and transmurally in the colon. Final immunohistochemistry were positive with SMA, CK and desmin without the expression of GIST markers (CD117, CD34 and DOG1) that confirmed leiomyosarcoma. One patient was diagnosed with diffused peritoneal metastasis at 6 months postoperatively and he died after 2 months of paliative care, another one is still on active surveillance. Discussion: LMS of the colon is a really rare entity and is only presented in clinical case reports. LMS has non-specific symptoms and is commonly diagnosed when it reaches a large size. Surgery is a mainstay treatment option. Nowadays, there is no clear evidence for the effectiveness of chemotherapy and radiation therapy. Conclusion: LMS is a rare neoplasm of colon. For the time being, there is no guidelines for treatment, but surgery still plays a fundamental role.