Unusual evolution of leiomyosarcoma of the rectum: a case report and review of the literature

BACKGROUND: Leiomyosarcoma of the rectum is a rare entity that comprises less than 0.1 % of all rectal malignancies. Given the uncommon nature of this tumor and the controversy about its treatment we report one case and review the literature in an attempt to report a particular evolution and to discuss the most appropriate treatment. CASE PRESENTATION: This case report describes the presentation of leiomyosarcoma of the rectum. A 30-year-old man from the north of Morocco presented with rectorrhagia and constipation. On physical examination we found a mass in his rectum approximately 6 cm from his anal margin. Pelvic magnetic resonance imaging showed a rectal mass with a parietal attachment that invaded the fascia and his perirectal tissue. Before any treatment he defecated spontaneously the tumor. On histopathological examination a diagnosis of leiomyosarcoma was made. An anterior resection of his rectum was performed with adjuvant radiotherapy at a dose of 50 Gy. After 1 year of surveillance, he has not presented any clinical symptoms and pelvic magnetic resonance imaging was normal. Unfortunately, histological analysis of a superficial biopsy of a rectal leiomyosarcoma may not be reflective of the entire tumor mass, and a diagnosis is based essentially on postoperative pathological examination. The optimal treatment modality in patients with rectal leiomyosarcomas is controversial. Prognosis is also poor; tumor size, histological grade, mitotic index, and local staging are the most known prognosis factors. CONCLUSION: The prognosis of rectal leiomyosarcoma is poor; more investigations are necessary to understand the progression of these tumors and to define an optimal treatment modality.