Coincidence or not? A rare case of rectal leiomyosarcoma amidst incidental findings of anal squamous cell carcinoma: case presentation and literature review.

Leiomyosarcoma accounts for only a small percentage of colorectal malignancies and remains a difficult disease to diagnose and treat. Here, we describe a case of leiomyosarcoma in a middle-age female first identified on colonoscopy. The cancer had invaded the posterior vaginal wall necessitating an abdominoperineal resection with partial vaginectomy and pelvic floor reconstruction with neovagina creation. Final pathologic analysis revealed invasion into the posterior vaginal wall without direct involvement of the vaginal squamous mucosa. Interestingly, a second carcinoma was found in the anal epithelium. Histology demonstrated this to be an anal squamous cell carcinoma positive for P16 immunohistochemistry, indicating HPV infection. Little is known as to whether leiomyosarcoma is also related to other carcinomas of the GI tract. This case of rectal leiomyosarcoma with temporal and spatial relationship to anal canal squamous cell carcinoma begs the question if HPV can trigger other neoplasms.