Primary Undifferentiated Pleomorphic Sarcoma of the Rectum

Abstract

Undifferentiated pleomorphic sarcoma (UPS) is a malignant soft tissue tumor that occurs primarily in the extremities and very rarely originates from the rectum. Here we report a 20-year-old male who presented with features of large gut obstruction. On digital rectal examination, a proliferative growth was felt at 4 cm from anal verge occupying whole of rectal lumen causing luminal narrowing. Computed tomography (CT) abdomen/pelvis revealed dilated colon secondary to a large, asymmetrical, lobulated, polypoidal enhancing lesion in rectum starting just above anal verge occupying and distending the whole rectum. Exploratory laparotomy with assessment of growth and sigmoid loop colostomy was performed under general anesthesia. Operative findings were a rectosigmoid growth with ascites. However, there were no distant metastasis in abdominal cavity. Proctoscopic biopsy was taken and came out to be pleomorphic sarcoma (undifferentiated) with positive vimentin and KI 67 on immunohistochemistry. Ultra-low anterior resection of tumor with closure of anal canal and end colostomy was performed. Histopathology of specimen confirmed undifferentiated pleomorphic sarcoma invading serosa (pT2a) with all 22 lymph nodes negative for tumor (N0). Patient is doing well after 14 months of surgery and has received 30 cycles (60 Gy) of radiotherapy and four cycles of chemotherapy. Undifferentiated pleomorphic sarcoma in the rectum is a rare malignant tumor with a poor prognosis. The main treatment for undifferentiated pleomorphic sarcoma is early complete resection. Adjuvant radiotherapy or chemotherapy can be attempted; however, till date, no data is available to support their role.