Yashaswini Basaboina, Rohini Avansta*, Abishek D and Abhimanyu B Punja
Department of Radiodiagnosis, K.S. Hegde Medical Academy, India
*Corresponding Author: Rohini Avansta, Department of Radiodiagnosis, K.S. Hegde Medical Academy, India.
Received: August 20, 2024; Published: August 26, 2024
Citation: Rohini Avansta., et al. “MDCT Evaluation of Colonic Malignant Villous Tumors". Acta Scientific Paediatrics 6.9 (2024):19-23.
Keywords: MDCT; Villous Adenomas
Adenomas of Colon are precursors of colorectal cancer [1]. They comprise about 50% of all colon and rectum polyps, with serrated and hyperplastic lesions contributing about 33% and mucosal polyps making up 10% [3,5]. They come in three subtypes: villous, tubular, and tubulovillous adenomas [2]. Tubulovillous subtype has 25 to 75% villous architecture, while villous adenomas have more than 75% villous architecture [7]. According to the literature, villous adenoma is a rare and more aggressive type with a large size with more lobules (10 are more) compared to a tubular adenoma and has greater chances of malignant transformation [1,5]. The risk of carcinoma is related to the proportion of villous change in an adenoma [2].
Villous adenomas develop from the surface epithelium with thin intervening fibrovascular cores. Compared to normal mucosa of the colon, there is an increase in the surface area of these lesions due to the villous configuration of the epithelium. The increased epithelium-to-connective tissue ratio gives these lesions a soft and compressible quality.
Villous adenomas usually are asymptomatic but can be symptomatic due to the larger size of the lesions, which may result in unusually high mucus output, obstructive manifestations, diarrhea, and occasional rectal bleeding. Villous adenomas may produce sodium, water, and potassium, resulting in higher secretory volumes mediated by prostaglandin E. Due to a larger area of the secretory surface, villous adenomas are related to electrolyte depletion syndrome [1].
Clinical diagnosis of these lesions is difficult due to the overlap of features. Few studies are available in the literature which described MDCT features of malignant villous tumors [2]. Even though it is noted in the literature that high- grade dysplasia and malignancy at imaging are somewhat challenging to detect [2], it is vital to detect, characterize, and determine the local extension of the lesion to plan treatment. This study aims to delineate MDCT features of colonic villous adenomatous tumors and the features favoring malignant transformation.
This is a retrospective study conducted from August 2020 to May 2023 on 11 patients who had MDCT diagnosis of malignant villous adenoma and were referred to the radiology department. The patients had clinical features of either bowel obstruction, suspected malignancy, or abdominal pain. The patients' basic demographic details and clinical diagnoses were recorded.
The distribution of males and females among 11 patients studied was 64%(7) and 36%(4), respectively. The age range of these individuals was 45-80 years. Most common presentation was non-specific lower abdominal pain (87%), followed by rectal bleeding (10%), and 3% had distension of the abdomen.
Most patients showed rectal involvement (55%). Other sites involved are the recto-sigmoid junction, sigmoid colon, and descending colon (Table 1).
In our study most of the villous tumors were solitary and showed irregular and cerebriform surface. The majority of the lesions had no pedicle compared to 9% of the pedunculated lesions. 73% of the lesions showed tuft of feeding vessels at the origin from the mucosal layer, which appeared like vascular pedicle. 91% of the lesions showed features of luminal occlusion (Table 2).
Most (91%) of the lesions in our study appeared to be > 2cm in size and showed irregular surfaces with heterogeneous enhancement patterns in contrast study (Table 2).
In our study, 55% of the lesions showed perirectal extension, and 63% showed metastatic extension to regional lymph nodes and distant organs. Liver was the most frequent site for distant spread and one into the lung (Table 3).
On histopathological examination most of the lesions were identified as Adenocarcinoma (63%) followed by high grade dysplasia (18%) and low grade dysplasia (18%) (Figure 1).
Villous adenomas are precursors of colorectal cancer and account for around 10% of all adenomas of the colon. They are equally prevalent in males and females and are usually seen in people between the ages of 50 and 80 [4,5]. In our study, the incidence in males was slightly higher than in females (7:4); and the age incidence was 45 to 80 years, matching the literature. They are usually found in the rectum and recto-sigmoid region but can occur elsewhere in the colon and gastrointestinal tract. The most common extracolonic location is the duodenum. In our study, most of the lesions were found in the rectum (55%). Other sites where they were frequent were recto-sigmoid, followed by the combination of recto-sigmoid and sigmoid colon (Table 1).
Adenomas are classified as diminutive, small, and large based on size, which is of a diameter of 1 to 5 mm, 6 to 9 mm, and ≥10 mm, respectively. Adenomas 10 mm or larger in diameter are considered advanced adenomas. Adenomas < 10 mm in size with at least 25% villous features or high grade dysplasia are also regarded as advanced adenomas [7]. These slow-growing lesions begin as benign adenomas, which can undergo malignant transformation. Villous adenomas can grow up to 10-15 cm in size while being benign. The size of polyps is significantly related to histopathologic findings and clinical characteristics [2]. In our study, the largest lesion encountered was about 12 cm and was well- differentiated adenocarcinoma. The size of the adenoma is a vital parameter to suspect the possibility of malignant transformation [1]. In our study, 91% of the lesions were > 2 cm in size (Table 2).
Villous adenomas are usually sessile but can also occur as polypoid and carpet- like lesions that cover a wider surface area [2,5]. Our study showed 91% of sessile lesions. Carpet-like lesions are flat, lobulated lesions covering a large surface area [2,5]. In our study, 18% of the lesions were of this type. Villous adenomas develop most frequently in the rectum [2] and in our study, 55% of the lesions were in the rectum (Table 1), and 82% were solitary (Table 2). Villous lesions are most often associated with luminal dilatation and occasionally lumen occlusion (Figure 3). In all the patients in our study, villous adenomas showed a convoluted gyral enhancement pattern giving a typical form of cerebriform appearance (Figure 6). This feature is because of the wrinkled surface similar to the sulcal and gyral pattern of the brain. In our study, cerebriform appearance was seen in 82% of the patients, and luminal occlusion was observed in 91% of the patients (Table 2). On barium studies, villous adenomas were described to have a sessile filling defect with a characteristic irregular mucosal pattern which was referred to as reticular, lacy, or feathery appearance because of the accumulation of barium in the interstices of the adenomas frond-like excrescences [5]. Similar appearance was noted in our study as the negative oral contrast was trapped in the villous interstices giving a corrugated appearance (Figure 6). This feature was one of the first reported findings by Smith., et al. [5].
In our study, 55% of the lesions showed perirectal extension (Table 2) (Figure 5). Broad-based soft tissue extensions from the lesion into the perirectal fat were more indicative of malignant change. The presence of pericolic lymph nodes was another feature associated with malignant changes. 63% of the patients in our study showed enlarged regional lymph nodes (Table 3).
Since villous adenomas are premalignant lesions, surgical removal is the treatment of choice. All patients in our study had undergone operative management followed by chemoradiation.
The main drawback of our study is that it is a retrospective study with a small sample size. A prospective study on a larger sample would have been better to establish the MDCT features of malignant villous tumors.
Villous adenomas are malignant-potential advanced lesions encountered during MDCT evaluation of the abdomen and pelvis. To help with management, it is crucial to identify these lesions and describe their extent. The MDCT appearance of villous adenomas and features of malignant change appears to be unique and pathognomonic. The MDCT features that are highly favoring villous tumors of the colon in our study were endophytic colonic lesions which show cerebriform surface or irregular convoluted appearance, which are sessile with a vascular tuft at the base, causing widening of the colon lumen with obstructive features in a patient with or without clinical suspicion. And the features highly suggestive of malignancy were local extension, regional lymph nodes and the presence of lesions in the liver/lung.
Imaging evaluation is important not only for lesion detection and characterization but for local extension before surgical excision to direct management and to decrease the incidence of adenocarcinoma. CT has an increasing role in diagnosing villous lesions even though many are detected incidentally on CT [1].
Copyright: © 2024 Rohini Avansta., et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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