A Case Report of Skip Lesions in Perianal Mucinous Adenocarcinoma

Nirali Shah,Imran Saeed,Michael Gates

doi:10.31579/2690-1897/064

Abstract

Perianal Mucinous Adenocarcinoma (PMA) is a rare gastrointestinal malignancy, known to occur in patients with a long-standing history of recurrent perirectal abscesses or a chronic fistula. In this case report, we present a unique presentation of perianal mucinous adenocarcinoma, which began as a rectal abscess and progressed to a case of perianal mucinous adenocarcinoma, with a skip lesion present all the way up in the mid-rectal region. To the best of our knowledge, this is the first case in which PMA presented with skip lesions as opposed to a continuous lesion, and presented without a long standing history of fistulas and recurrent abscesses, but instead just a 4-day history of perianal burning, itching and tingling. The use of CT imaging, MRI’s and PET scans as diagnostic modalities for PMA are further elucidated in the report, along with a discussion of NCCN guidelines on using radiation therapy followed by an APR with inguinal node dissection for the management and treatment of PMA. Sharing this unique and atypical presentation of PMA with multimodality speciality groups and tumor boards helps in the development of various diagnostic and therapeutic approaches for PMA, as well as enhances our understanding of this rare malignant entity.

Highlights

Perianal mucinous adenocarcinoma (PMA) is a rare, malignant entity constituting 2-3% of all gastrointestinal malignancies[1]
We present a unique presentation of perianal mucinous adenocarcinoma, which began as a rectal abscess and progressed to a case of perianal mucinous adenocarcinoma, with a skip lesion present all the way up in the mid-rectal region
There is a wide variability in the clinical presentation of cases of perianal mucinous adenocarcinomas

Summary

Introduction

Perianal mucinous adenocarcinoma (PMA) is a rare, malignant entity constituting 2-3% of all gastrointestinal malignancies[1]. Patients with PMA tend to present with perianal pain and itchiness, bleeding per rectum and in most cases an ulcerative growth or a palpable mass with a bloody or mucoid discharge[2] Most of these cases tend to be preceded by a symptomatic period of 4-6 months, and the patient population to commonly present with PMA includes those with a past medical history of HIV, IBD or recurrent and long-standing fistulas and abscesses[4]. Upon follow-up with the colorectal surgeon 5-days later, another rectal exam revealed a 2-cm soft tissue growth in the form of a mildly tender and fluctuant mass, located in the right perirectal quadrant, close to the anal verge It appeared to be a warty lesion and upon pressing the lesion, a gelatinous mucinous material was found to exude out. D. (a) CT scan of the rectal lesion. (b) Fluid collection in the perirectal area is appreciated E

PET scans of the rectal lesion showing hot focus in the perirectal abscess

Findings

Discussion