Soft tissue tumors of the anorectum: rare, complex and misunderstood

Beyond adenocarcinoma: MRI of uncommon rectal neoplasms and mimickers

OBJECTIVE

To provide a review of rare rectal tumors beyond adenocarcinoma.

RESULTS

Rectal cancer is a common malignancy, both in the United States and abroad. In addition to adenocarcinoma, abdominal radiologists will encounter a variety of other less common rectal masses, both benign and malignant neoplasms as well as non-neoplastic mimickers. Familiarity with these conditions and their characteristic features on MRI is useful in clinical practice. In this article, a number of such conditions are discussed, with an emphasis on distinguishing features on MRI of the rectum.

CONCLUSION

Familiarity with the MRI features of rare rectal tumors beyond adenocarcinoma, as well as a small number of non-neoplastic mimics, is important for abdominal imagers to make diagnostic differentials and to assist in treatment planning.

Systematic review of anorectal leiomyosarcoma: Current challenges and recent advances

BACKGROUND

The anorectal leiomyosarcoma (LMS) is an aggressive malignant neoplasm. Owing to the rarity of LMSs, an optimal treatment modality has yet to be determined.

AIM

To collect all published data on anorectal LMS characteristics, explore current treatment options, and review recent cases of postradiation LMS.

METHODS

A literature search of the PubMed electronic database was conducted using the MeSH terms “rectal neoplasms”, “anus neoplasms” and “gastrointestinal neoplasms” combined with “leiomyosarcoma”. The search was limited to English language and human studies. All available case reports and case series of anal or rectal LMSs that were published from the beginning of January 1996 to May 2017 were included if the diagnosis of LMS had been confirmed by histopathologic examination. Data were analyzed using simple statistics (mean, median, and standard deviation). Independent sample t-test was used to compare means for continuous variables.

RESULTS

A total of 27 articles reporting on 51 cases of anorectal LMS were identified. Among these cases, 11.7% had undergone previous pelvic radiotherapy (developing LMS at 13-35 years afterwards). Anorectal LMS affected the rectum in 92.2% of the cases, and no sex-based predominance was observed. Surgical resection with negative margins remains the mainstay of treatment, which can be accomplished with wide local excision or radical resection. The local recurrence rate was higher among cases who received wide local excision (30%), as compared to radical resection (20%); however, the overall rate of metastasis was 51.61% regardless of the treatment approach. The use of neoadjuvant radiation lowers the risk of local recurrence compared to adjuvant radiotherapy, and facilitates R0 resection of the tumor. Cases treated with adjuvant chemotherapy showed better rates of distant recurrence and overall survival. Nonetheless, multidisciplinary team discussion is necessary to determine the optimal management plan whilst considering patient- and disease-related factors.

CONCLUSION

A multidisciplinary team approach, considering the underlying patient- and disease- related factors, is necessary for optimal management of these complex tumors.

Local excision of rectal schwannoma using transanal endoscopic microsurgery: A case report

INTRODUCTION

Schwannoma is a neoplasm originating from the neural crest cells (schwann cells) that form nerve sheaths. These tumors are thought to be benign with little risk of malignant transformation. They rarely affect the gastrointestinal tract, and primary rectal involvement is extremely rare. Until 2013, only 11 cases of anorectal schwannoma have been reported. Optimal surgical treatment of rectal schwannoma has not been established.

PRESENTATION OF CASE

We herein describe a 70-year-old woman with a submucosal tumor arising from the posterior wall of the rectum with features mimicking a gastrointestinal stromal tumor. After discussing the operative procedures and obtaining written informed consent, we attempted local excision of the tumor using a transanal endoscopic microsurgery (TEM). The tumor was proved to be S-100 positive schwannoma on immuhistochemical studies. Her postoperative course was uneventful, and there is no evidence of tumor recurrence as of 6 months after surgical excision.

DISCUSSION

An extremely rare rectal schwannoma was successfully treated using a TEM without compromising anorectal function.

CONCLUSION

TEM is a feasible approach for local excision of rectal tumors with low risk of malignancy.