Urachal Mucinous Cystic Tumor of Low Malignant Potential with Concurrent Sigmoid Colon Adenocarcinoma

Kelly Brennan,Heather Curtis,Thomas Arnason,Paul Johnson

doi:10.1155/2019/1434838

Kelly Brennan, Heather Curtis + Show 2 more

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https://doi.org/10.1155/2019/1434838

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Abstract

Urachal mucinous tumors are rare neoplasms with behaviour that can range from relatively benign to malignancy that can spread distantly or throughout the peritoneum as pseudomyxoma peritonei or peritoneal carcinomatosis. Here we describe a unique case of urachal mucinous cystic tumor of low malignant potential confined to an intact cyst at the dome of the urinary bladder, without rupture or peritoneal spread. The urachal mucinous tumor was an incidental finding on a staging CT scan performed for sigmoid colon adenocarcinoma. We believe that this case illustrates a potential diagnostic pitfall which could have prognostic and therapeutic implications. Due to the intestinal phenotype of these neoplasms, a urachal tumor of low malignant potential could be mistaken for metastatic spread from a colonic adenocarcinoma in the rare situation such as this case, where the two neoplasms occur concurrently.

Highlights

Urachal neoplasms are thought to arise from neoplastic transformation of remnant urachal tissue left from incomplete regression of the urachus in fetal development [1,2,3,4,5,6,7,8,9,10,11]
In this report we describe a unique patient with a clinical presentation that defies this convention. This patient presented with a urachal mucinous cystic tumor of low malignant potential and a concurrent invasive adenocarcinoma of the sigmoid colon
The cyst was felt to be best classified as a urachal mucinous cystic tumor of low malignant potential, based on the classification system described by Paner et al [12]

Summary

Introduction

Urachal neoplasms are thought to arise from neoplastic transformation of remnant urachal tissue left from incomplete regression of the urachus in fetal development [1,2,3,4,5,6,7,8,9,10,11]. The spectrum of cystic urachal mucinous neoplasms (described in Table 2), including mucinous cystadenoma, mucinous cystic tumor of low malignant potential, and mucinous cystadenocarcinoma [12], is similar to the morphologic spectrum of appendiceal [13] and ovarian [12, 14] intestinal-type mucinous neoplasms. The absence of a known primary glandular neoplasm at another anatomical site has been put forward as a criterion for pathologic diagnosis of a urachal mucinous neoplasm [12, 15]. In this report we describe a unique patient with a clinical presentation that defies this convention This patient presented with a urachal mucinous cystic tumor of low malignant potential and a concurrent invasive adenocarcinoma of the sigmoid colon. We believe that the differences in morphology, beta-catenin immunohistochemistry, and the distinct anatomical locations of the two tumors rule out metastasis from one site to the other

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