Operative choice was most

often dictated by high cellularity and tumor size rather than anatomic location (6). Higher rates of recurrence have been reported with local excision (67%) compared to APR (19%) in some series (17). In contrast, other series report similar outcomes regardless of surgical approach (18,19). Anorectal LMSs were traditionally thought of as resistant to both chemotherapy and radiation. However, this notion is largely based on sporadic case reports (19) or publications predating the advent of megavolt radiotherapy. More recent experience suggests a possible role for pre-operative Inhibitors,research,lifescience,medical chemotherapy and/or radiotherapy in sphincter preserving surgeries, but the relatively Inhibitors,research,lifescience,medical small series do not allow U0126 definitive conclusions (10,20,21). LMSs rarely metastasize through lymphatics and are more likely to spread through the lungs and liver through hematogenous spread (22-24). Recurrence rates for anorectal LMS are associated with high histological grade, large tumor size and incomplete surgical resection (16). Five year survival reported as varying between 20-25% with Inhibitors,research,lifescience,medical poor prognosis overall in rectal leiomyosarcomas (25-28). Rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is one of the most common childhood soft tissue tumors, but represents less than 5% of malignant soft tissue lesions in adults (29-31). Anorectal presentation is extremely rare and is seen in less than 2% of cases (32). In this location, these Inhibitors,research,lifescience,medical tumors are thought to arise from the muscular layers of the bowel and the genitourinary tract. Most of the data on this disease originates from studies conducted between 1972 and 1997 by the Intergroup RMS Society for the RMS population aged 0-21 years (33). In these studies, cases with anorectal involvement were analyzed separately and a practice guideline has been developed (discussed below) (34). Although, Inhibitors,research,lifescience,medical designed originally for children, it is also used for adults, due to the small number of RMS cases in this population (35). It has been postulated that perineal RMS occurring at a younger age may have

a genetic predisposition and is related to other genetic syndromes such as Nijmegen breakage syndrome (36). No similar syndromic associations have been observed in adults. RMS is described as a grossly uncircumscribed CYTH4 lesion with multiple areas of spherical growth, often resembling a “bunch of grapes” that is soft in consistency. Histologically, it is divided into three major types: embryonal, including spindle and botryoid subtypes, alveolar and undifferentiated (37). As a result of its mesodermal/muscle tissue origin, RMSs tend to show multiple areas of muscle tissue at different stages of development. Embryonal type shows a spindle shape pattern often arranged in patches of highly cellular areas alternating with sparsely cellular areas containing mucoid cytoplasm which is often a hallmark of the diagnosis (38).