Lesion Sessile

C-RADS describes the use of three morphologies of lesions sessile (broad based lesion whose width is greater than its vertical height), pedunculated (polyp with a separate stalk), and flat (polyp with vertical... 

During a 17-year period, 83 workers in a benzidine department were examined cysto-scopically 34 workers had congestive lesions, 3 had pedunculated papillomas, 4 had sessile tumors, and carcinoma was found in 13 of the workers. ... 

Melanosis coli occurred in a 39-year-old liver transplant patient who took an over-the-counter product containing aloe, rheum, and frangula (4). The typical brownish pigmentation of the colonic mucosa developed over 10 months. The medication was withdrawn and follow-up colonoscopy 1 year later showed normal looking mucosa. However, a sessile polypoid lesion was found in the transverse colon. Histology showed tubulovillous adenoma with extensive low-grade dysplasia. 

The fatty streak, which is found at a young age ubiquitously among the world s population, consists of smooth muscle cell aggregates surrounded by cholesteryl ester deposits it is a sessile lesion that does not obstruct and presents no clinical symptoms. 

Sheridan TB, Fenton H, Lewin MR, et al. Sessile serrated adenomas with low- and high-grade dysplasia and early carcinomas an immunohistochemical study of serrated lesions caught in the act. Am J Clin Pathol. 2006 126 564-571. 

Types of papillomata were separated by Hodgson and Whitely into four morphologic groups (1) flat shiny lesions (2) sessile lesions resembling plantar warts (3) pedunculated skin tags (fibro-epithelial polyps) and (4) plaques (seborrheic keratoses). 

Papillomas generally result between 6 months and 43 years after exposure. The shiny and sessile lesions mainly occur on exposed skin of the hands and forearms. Interestingly, there were more benign papillomata in their control group (73%) than in the pitch workers (58%) (Hodgson and Whitely 1970). 

Fig. 4.8. Patient with right sided sigmoid. There is tagged stool (arrowhead). There is also non-tagged material (orrow). This should be considered a lesion unless the contrary is proved. A correct diagnosis of an 8-mm sessile polyp was made...

Fig. 4.19.a Non-tagged foam with some tiny tagged residue besides a possible sessile polyp (black arrowhead) in the ascending colon (supine view), b Corresponding prone view the foam has moved to the anterior border of the ascending colon (white arrow). The sessile lesion remains unchanged (black arrowhead) and should be considered a sessile polyp. The lesion was confirmed on optical colonoscopy... 

Fig. 6.1a,b. Colonic phantom containing three different simulated lesions 9.6-mm and 5.5-mm sessile polyps and 8-mm flat lesion. Using a a thick collimation protocol lesions sharpness is definitely reduced compared with b a thin collimation protocol. Note edge blurring (arrow) directly related to the increase of effective slice thickness as well as geometric distortion. This artefact particularly affects simulated flat lesion (arrowhead)... 

Future Advances in Image Display Techniques Different Categories of Colorectal Morphologies 76 Focal Polypoid Lesions (r/o stool) 76 Pedunculated Lesions 79 Sessile/Flat Lesions (r/o thick or confluent Folds) 79 Advanced Mural Lesions (r/o collapse) 81 Standardization of Reporting of Clinically Significant Colorectal Findings 82 References 85... 

There are common types of colorectal morphologies evaluated in CT colonography. These include the focal polypoid lesion, pedunculated lesion, flat or sessile lesion and advanced mural lesions. This section will describe these morphologies and their corresponding false positive counterparts. The differential application of 2D and 3D image displays to assess these morphologies will also be reinforced. 

Fig.7.3a,b. Polypoid lesions with focal pockets of air seen in true polyp vs stool, best shown in axial 2D MPR a true positive sessile polyp (arrow) with air around edges of lesion (arrowheads), where lesion abuts the wall b false positive of stool (arrow) with central pockets of air (arrowheads)... 

The most common false positive counterpart to the flat or sessile lesion is a thickened fold or conflu-... 

Larger Flat Lesions 96 8.2.23 Small Sessile Polyps 96... 

Fig. 8.5a,b. False negative diagnosis polyps simulating fecal residue in mobile segments. Differential diagnosis of mobile stool or small sessile lesions in a mobile transverse colon a supine scan shows two lesions in the transverse colon, (arrows) b prone scan shows the lesions in the transverse colon in an apparent different position (arrows). Conventional colonoscopy revealed the presence of two small sessile polyps. Lesson Polyps, located in mobile colonic segments such as the transverse colon can cause erroneous diagnosis of mobile residual stool... 

Although sessile polyps have a high conspicuity, if located between folds (Fig. 8.11), those lesions may remain undetected in case the lesions are located on a semilunar fold (Fig. 8.12). 

Small flat lesions will be missed, even on retrospective analysis, for the same reason as small sessile lesions small lesions are just more difficult to visualise (Macari et al. 2003) (Fig. 8.13). 

First of all, there is the problem of insufficient awareness and familiarity with those lesions surveillance programs, based on the known adenoma-carcinoma sessile or pedunculated lesion, have mainly focused on identifying sessile of pedunculated polyps. This explains why flat lesions are frequently characterised as normal folds. As a rule, a thickened fold in an otherwise well distended colon should raise the question whether or not this lesion could represent a flat lesion. 

Small sessile polyps frequently represent hyperplastic polyps. Hyperplastic lesions tend to flatten out in well distended segments, explaining the fact that those lesions might only be visible in somewhat underdistended segments. In that way, those lesions are frequently only recognised on either prone or supine position, and can therefore be mistaken as residual stool. 

Sessile cancers, if detected, may remain unrecognised by the fact that the lesions are characterised as normal fold correlating axial 3D images with endo-luminal views is helpful in this respect (Fig. 8.18). 

Lesion size (mm) For lesions 6 mm or greater, single largest dimension of polyp head (excluding stalk if present) in either, MPR, or 3D views. The type of view employed for measurement should be stated Sessile-broad based lesion the width of which is greater than the vertical height Pedunculated-polyp with stalk... 

The diffuse form presents with multiple polypoid lesions and is called diffuse mucosal nodularity or malignant lymphomatous polyposis (O Connell and Thompson 1978 Callaway et al. 1997). The polyps appear smooth and sessile but can also be irregular or pedunculated. Often, the entire colon or a long segment is involved. 

Fig. 14.23a-c. Sessile polyp a supine 2D axial image and b 3-D endoluminal view demonstrate a polypoid filling defect in the ascending colon c after changing to soft tissue window setting, the homogenous soft tissue attenuation of the lesion is demonstrated. Colonoscopy demonstrated a 1.5 tubulovillous adenoma... 

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