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17 Lipomas oftheColon

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a(i) a(ii)

a(iii) a(iv)

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Fig. 17.1 (a) (i) 3D endoluminal view showing polypoi- dal lesion (closed white arrow) arising from haustral fold (open white arrow). (ii) 3D translucent display of lipoma. Green=fat (open white arrow) and barium on tip (closed

white arrow). (iii) Axial 2D soft tissue window view showing tip of barium (open white arrow) on lipoma (closed white arrow). (iv) 3D prone image shows barium covering lipoma (open white arrows).

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a(v) a(vi)

b(i) b(ii)

J. H. Bortz

Fig. 17.1

showing lling defect lipoma (closed white arrow) in barium pool. (vi) Translucent display showing diffuse inltration of ICV (open white arrow) indicating caecal

(v) Prone 2D axial soft tissue window view

17.5 Lipoma ‘Signs’ at Optical

Colonoscopy

During optical colonoscopy, the following signs of lipoma may be present.

1. The ‘tenting’ sign means gripping the mucosa

with forceps and ‘pulling’ or ‘tenting’ it away from the underlying mass [4, 11].

lipomatosis with minimal high tissue intensity (red). (b) (i) 3D view shows a lipoma on ICV (open white arrow). (ii) Translucent display shows dense green colouration (closed white arrow), which is in keeping with fat (lipoma)

2. The ‘cushion’ or ‘pillow’ sign reects the spongy nature of the mass when indented with a closed biopsy forceps. As the forceps is withdrawn, the tumour will spring back to resume its previous original shape [15].

3. ‘Naked fat sign’ means the adipose tissue may protrude through the biopsy site which reveals the fatty characteristic of the tumour [16].

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Key Messages

There are several points to bear in mind when evaluating CTC studies.

• Lipomas are more common in women in their sixth decade.

• The right colon is the most common site.

• The incidence of lipoma has been reported between 0.2 and 4.4%.

• There is usually a solitary colonic lipoma.

• A lipoma may be sessile or pedunculated.

• Lipoma size may vary: from <20 to >40mm.

• Symptoms are usually related to the size of the lipoma: those less than 30 mm are usually symptom free, but if the size increases to >40 mm, the patient may become symptomatic.

17.6 Summary

CTC is useful for detecting and demonstrating colonic lipomas on 2D and 3D views. These benign lesions usually cause no symptoms until they reach a large size. Small lesions can be safely left in the colon, but as size increases >30mm, symptoms may the occur. There are two treatment options: endoscopic removal of lesions <30mm, or surgical resection for benign larger tumours or those that result in intussusception.

References

1. Zhang H, Cong J, Chen C, Qiao L, Liu E.Submucous colon lipoma: a case report and review of the literature. World J Gastroenterol. 2005;11(20):3167–9.

2. Tascilar O, Cakmak GK, Gün BD, Ucan H, Balbaloglu H, et al. Clinical evaluation of submucosal colonic lipomas: decision making. World J Gastroenterol.

2006;12(31):5075–7. [cited 2022 September 20].

www.wignet.com.

3. Agrawal A, Singh KJ. Symptomatic intestinal lipomas: our experience. MJAFI. 2011;67(4):374–6.

https://doi.org/10.1016/S0377- 1237(11)60090- 7.

4. Heiken JP, Forde KA, Gold RP.Computed tomography as a denitive method for diagnosing gastrointestinal lipomas. Radiology. 1982;142:409–14.

5. Ott DJ, Gelfand DW.The future of barium radiology. BJR. 1997;70:S171–6.

6. Bortz JH. In the era of CT colonography, is there any role left for barium enema in the investigation of colonic disorders? SAR. 2014;52(2):13–20.

7. Mohamed A, Hassan N, Bhat N, Abukhater M, Uddin M.Caecal lipoma, unusual cause of recurrent appendicitis, case report and literature review. Internet J Gastroenterol. 2008;8(1). [Cited 2022 September 20].

https://ispub.com/IJGE/8/1/10579.

8. Nebbia J, Cucchi J, Novellas S, Bertrand S, Chevallier P, Bruneton JN.Lipomas of the right colon: report on six cases. Clin Imaging. 2007;31(6):390–3. https://

doi.org/10.1016/j.clinimag.2007.06.021.

9. Krishnan P, Adlekha S, Chadha IT, Babu AK.Rectal lipoma associated with genital prolapse. Ann Med Health Sci Res. 2013;3(Suppl 1):S18–20. https://doi.

org/10.4103/2141- 9248.121212.

10. Motamedi AK, Dehestani A, Kadivar M. Colon lipoma: a case report and review of the literature. Med J Islam Repub Iran. 2006;20(3):151–4.

11. Roknshari S, Ricci Z, Kobi M, Huo E, Yee J.Colonic lipomas revisited on CT colonography. Abdom Radiol. 2022;47(5):1788–97. https://doi.org/10.1007/

s00261- 022- 03489- 2.

12. Nallamothu G, Adler DG. Large colonic lipomas. Gastroenterol Hepatol. 2011;7(7):490–2.

13. Vagholkar K, Bendre M. Lipomas of the colon: a surgical challenge. Int J Clin Med. 2014;5:309–13.

https://doi.org/10.4236/ijcm.2014.56046.

14. Jiang L, Jiang LS, Li FY, Ye H, Li N, Cheng NS, Zhou Y. Giant submucosal lipoma located in the descending colon: a case report and review of the literature. World J Gastroenterol. 2007;13(42):5664–7. https://

doi.org/10.3748/wjg.v13.i42.5664.

15. Ryan J, Martin JE, Pollock DJ.Fatty tumours of the large intestine: a clinicopathological review of 13 cases. Br J Surg. 1989;76(8):793–6.

16. Notaro JR, Masser PA. Annular colon lipoma: a case report and review of the literature. Surgery. 1991;110(3):570–2.

Extracolonic Findings, Their

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Clinical Signicance, andtheRole ofOpportunistic Screening

JoelH.Bortz

18.1 Introduction

Extracolonic ndings (ECFs) are not the goal of CT colonography (CTC). However, radiologists, and radiographers who have been trained to provide a preliminary report [1–3] are responsible for evaluating both intracolonic and extracolonic ndings. Should a CTC study be of nondiagnostic quality (e.g., poor bowel preparation or distension or a combination of the two) we are still able to do a full inspection of all extracolonic structures. We would not report on the poor quality CTC, but we denitely must report all ECFs as a CT scan includes the lower chest, abdomen, and pelvis.

CTC is an acknowledged method of investigation of asymptomatic individuals for colorectal cancer (CRC) who are 45years or older. It has the added ability to detect extracolonic lesions in the abdomen and pelvis. These lesions are classied as either clinically important or unimportant [4]. The denition of a clinically important nding is one that necessitates further diagnostic studies or medical/surgical follow-up. ECFs were identied in 63% of patients in a study by Yee etal. [4]. Fourteen percent had lesions that were considered clinically important, and most of these ndings had not been previously diagnosed.

J. H. Bortz (*) LSG Imaging, Los Angeles, CA, USA

It is important to clearly balance the benet and harm that comes from ECFs [5]. Findings of a review of 24 studies were that approximately 20% of indeterminate renal masses detected with CTC were ultimately malignant [6].

Since the extracolonic abdomen and pelvis are screened with a low-dose technique without the use of an intravenous (IV) contrast medium, radiologists, and appropriately trained radiographers, must be aware of the potential pitfalls [7]. The benet of detecting important or signicant ndings in a small minority of patients is huge, particularly in nding cancers that can be treated at an early pre-symptomatic stage. Possible downside includes undue anxiety and added costs incurred by additional studies [8].

There is a very low rate of detected signicant ndings (usually <10%) in most CTC studies in asymptomatic individuals. In a study by Pickhardt etal. [9], the prevalence of polyps (≥10mm) was 7%; the prevalence of colon cancer was 0.2% (2 per thousand); and prevalence of ECFs was

0.35%. A disclaimer should be in CTC reports, namely that the lack of IV contrast material and low-dose technique limit the evaluation of CT ndings outside the colon.

For many years, the costs of investigating ECFs have been debated. Concern has been expressed that if multiple benign ECFs are investigated, then costs will be driven-up signicantly without inuencing the nal outcome.

https://doi.org/10.1007/978-3-031-30866-6_18

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Another debate pertains to causing unnecessary worry that a lesion may be malignant, but turns out to be benign. A study of 264 patients in 2000 reported: (1) out of the 41% of the patients with ECFs, 115 were considered signicant ndings, and (2) the additional cost of the work-up of the ECFs was $28 per CTC examination [10]. ECFs were identied in 69% of patients in a study of 681 asymptomatic patients: 10% of the ECFs were highly signicant ndings. The additional cost of investigating these patients was $34.33 per CT examination performed [11].

Extracolonic evaluation at CTC entails the

following technique.

• Use of 1.25 mm collimation during CT scanning

• Exposure selection: 120kVp and 50–75mAs

• No IV contrast media

• Automatic reconstruction of 5mm contiguous CT slices.

– Advantage of 5mm contiguous reconstruc-

tion include:

(a) Fewer number of slices (<100) as

opposed to approximately 1000 slices (b) Decreased image noise (c) Easier retrieval and archiving in a

PACS system.

ECFs are assessed using a low-dose CT technique as well as the absence of IV contrast [7]. CTC screening for CRC is a low-dose examination which may compromise the detection of extracolonic abnormalities due to increased image noise. An IV contrast medium is not routinely used in CTC screening for several reasons.

1. It does not increase polyp detection.

2. It adds to cost of the examination.

3. It extends the time of examination.

4. It increases risk to the patient in terms of pos-

sible adverse reactions.

For viewing of ECFs, automatic reconstruction of the supine study to 5mm contiguous images is performed in all cases. There are several advantages in making the images 5mm thick, namely

• fewer images to review

• decreased image noise

• easier to archive and retrieve the images

However, IV contrast media are used when a study becomes diagnostic or when a carcinoma is identied, either within or outside the colon; an increase in tube current is then required which means increased dose to the patient [4]. CTC unavoidably targets the pelvic tissues and extracolonic abdominal tissues [6]. In other words, CTC potentially detects disease in organs other than the colon. For example, 20% of indeterminate renal masses detected at CTC are malignant. The majority of ECFs are not of clinical importance, whilst a small percentage (7–11%) of patients undergo further testing because of the initial ECF [5, 12, 13]. An almost equal number of extracolonic cancers and intracolonic cancers were identied in a 2010 study of 2277 patients undergoing CTC screening [14]. Extracolonic detections increased with age. Macari etal. [15] reported 74% of patients >65 years had extracolonic abnormalities compared with 55.4% in younger patients. In a UK study, 67% of older symptomatic patients had extracolonic abnormalities [16].

The following abbreviations are used in this chapter.

• AAA: abdominal aortic aneurysm

• AAC: abdominal aortic calcication

• AI: articial intelligence

• BMD: bone mineral density

• CRC: colorectal cancer

• DXA: dual-energy X-ray absorptiometry

• E1: not of clinical importance

• E2: low clinical importance

• E3: moderate clinical importance

• E4: high clinical importance

• ECFs: extracolonic ndings

• FRAX: fracture risk assessment tool

• HU: Hounseld unit

• ML: machine learning

• ROI: region of interest

• TBS: trabecular bone score

18 Extracolonic Findings, Their Clinical Signicance, andtheRole ofOpportunistic Screening

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18.2 Benets ofVisualising Extracolonic Organs and Tissues

Signicant pathology may be identied in approximately 10% of cases. For example, early cancers of the kidney and ovary, as well as abdominal or pelvic lymphadenopathy in underlying lymphoma. Abdominal aortic aneurysms >30 mm in transverse diameter may be detected incidentally [11,

14]. Visualisation of such pathology is not possible

with other CRC screening tests. It is however important to balance the benets and harms when ECFs are noted at CTC.In a study undertaken by Plumb et al. [5], it was found that patients were prepared to tolerate an extremely high rate (>99.8%) of unnecessary additional imaging or invasive testing to reap the potential benets of nding an early stage extracolonic malignancy. Conversely healthcare professionals were less tolerant as only 40% of physicians accepted the need for follow-up studies, and only 5% accepted the need for further invasive studies. In terms of patient care, the false-positive rate of screening CTC for ECFs is highly acceptable; for both patients and healthcare professionals. Patients, for example, would tolerate over 4000 false-positive diagnosis to avoid a single missed CRC [17].

cysts, are of low clinical importance and do not impact on patient management. Those that do impact on management, and are therefore of high importance, include extracolonic malignancies such as renal or ovarian neoplasms, and abdominal aortic aneurysms. Lesions, especially renal carcinoma, that are identied early tend to be more curable [18]. It has been shown that more extracolonic cancers are detected than colon cancers during CTC.The former are identied in 3.5 cases/1000 whereas colon cancer is identied in

2.1 cases/1000 cases [19]. More than half of patients with symptoms of CRC are found to have extracolonic pathologies by CTC analysis [20].

Abdominal aortic aneurysms (AAAs) are most commonly located in the infra-renal portion of the aorta. Development of an AAA usually occurs in males, and in patients older than 65years with a history of smoking or hypertension. The majority of cases of AAA (62%) are incidental ndings [4]. A contrast medium is not used in screening CTC studies to diagnose AAAs. In order to be diagnosed, they must measure at least 30mm (3cm) in their widest diameters. The risk of a rupture of an AAA increases as it grows in size; surgery or endovascular repair is required when an AAA is >50mm.

18.2.1 Negative Aspects ofECFs

The negative aspects of extracolonic ndings include:

(a) added diagnostic cost (b) time consuming to evaluate these ndings,

thus adding to overall reporting time

ety and risks. Especially following biopsies, or exploratory surgery for what turns out subsequently to be an insignicant nding [4].

18.3 Clinical Importance ofECFs: Low, Moderate, andHigh

It is useful to divide ECFs in asymptomatic patients into three categories: low, moderate, and high importance. Benign lesions, such as kidney

18.4 Classication ofECFs

Zalis etal. [21] classied ECFs in terms of their clinical importance, namely

• low importance: low clinical importance thus no immediate impact on patient management

• moderate importance: usually benign but may require further work-up

• signicant importance (= medically important)

ECFs may be either clinically insignicant or

signicant, depending on whether additional workup is required. For example, if a pleural effusion is visualised it would be classied as E3: moderate clinical importance. Visualisation of a simple renal cyst would be classied as E2: low clinical importance. Examples of ECFs for each level of clinical importance are presented in Table18.1. A revised classication of ECFs is a work in progress and should be published within the next few months.

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Table 18.1

E classication

E0 Limited examination E1 Not of clinical importance

Normal examination or anatomic variant

No extracolonic abnormalities visible Anatomic variant, for example, retro-aortic left renal vein, BMD >160 HU, air in vagina normal causes

E2 Low clinical importance

Clinically unimportant ndings

No work-up indicated. Examples are presented below. Liver, kidney: simple cysts Non-obstructing renal stones Non-obstructing gall stones Gallbladder: cholelithiasis without cholecystitis Vertebra: haemangioma Arterial calcication Calcied granuloma Uncomplicated hernias (inguinal, hiatal, femoral, enterocoele) Various skeletal abnormalities Adrenal adenomas Renal calculi Fatty liver Lipoma Uterine broids BMD between 100 and 160 HU

E3 Moderate clinical importance

Likely unimportant nding and likely to be benign. Incompletely characterised NB: In nearly all cases of asymptomatic patients, these lesions prove to be benign

Further work-up may be indicated Kidney: minimally complex or homogeneously hyper-

attenuating cyst Complicated renal cysts Prominent adnexal lesions in women Indeterminate pulmonary nodules Indeterminate liver lesions Pleural effusions Cardiomegaly Splenomegaly Complicated hiatus hernias BMD <100 HU Air in vagina due to pathology Metabolic- associated fatty liver disease (see Chap. 19)

E4 High clinical importance

Potentially important nding. Communicate to referring physician as per accepted practice guidelines NB: Appendicitis, diverticulitis, pancreatitis, irreducible inguinal hernia,

Kidney: solid renal mass Liver masses Lymphadenopathy ≥10mm Vasculature: aortic aneurysms >50mm Lung: non- uniformly calcied pulmonary nodule ≥10mm Irreducible inguinal hernia containing large bowel

pneumothorax, pneumoperitoneum must be communicated to the referring physician/ health practitioner

It must be remembered that an extracolonic evaluation is limited by lack of IV contrast and the low-dose CT technique

Adapted from Zalis etal. [21]

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18.5 Examples ofECF Images

It is important that every organ and bony structure is carefully evaluated on every CTC image [22]. The E-classication in Table18.1 is used to present examples in each classication. As evident in these examples, the majority are classied as being of low clinical importance (E2). Only a

few are classied as being of signicant clinical importance (E4).

18.5.1 E1: Not ofClinical Importance

Figure 18.1a–g are examples of ECFs that are not of clinical importance.

Fig. 18.1 (a) 2D axial shows normal pericardium sur- rounding the heart (yellow arrow). (b). 2D axial showing normal right posterior descending coronary artery (yellow arrow). (c) 2D axial view showing pulmonary vessels (open

white arrows). 1 = anterior mediastinal fat; 2 = liver; 3=right ventricle; 4=right atrium; 5=inferior vena cava; 6=aorta; 7=serratus anterior; 8=latissimus dorsi muscle; 9=quadratus lumborum; 10=erector spinae muscles.

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d(i)

d(ii)

Fig. 18.1

renal vein (open white arrow). LK=left kidney; RK=right kidney; A=aorta. (ii) 2D axial view showing normal renal vein (open white arrow). RK=right kidney; LK=left kidney; A= aorta. (e) 1 = right lobe of liver; 2=left lobe of liver; 3= aorta; 4 = spleen; Open white arrow = splenic artery calcication. (f) 2D coronal view of a left lateral decubitus study showing splenic impression on splenic exure of

(d) (i) 2D axial view showing retro-aortic left

colon (open red arrows). Open white arrow=rectal catheter; 1=hepatic exure of colon; 2=aorta; 3=splenic exure; 4=spleen; 5=psoas muscle; 6=sigmoid colon; 7=ischium of pelvis; 8 = greater trochanter of femur; 9 = rectum; 10=contrast in ascending colon; 11=caecum. (g) 2D axial shows ovary pressing on bowel (open white arrow)

18 Extracolonic Findings, Their Clinical Signicance, andtheRole ofOpportunistic Screening

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18.5.2 E2: Low Clinical Importance

Figure 18.2a–aZ (ii) are examples of ECFs that are of low clinical importance.

247

Fig. 18.2 (a) 2D axial view. 1=breast implant; 2=col- lapsed left breast prosthesis (closed white arrow); 3=left ventricle; 4 = right atrium; 5 = distal oesophagus; 6 = descending aorta; 7 = serratus anterior muscle; 8=latissimus dorsi muscle. Rib=open white arrow. (b) 2D axial view of a patient who had a left mastectomy (open white arrow). 1=right breast; 2 liver; 3=left ventricle; 4=distal oesophagus; 5=descending aorta. (c) 2D axial view shows artefact from pacemaker wires (open yellow arrows). Small hiatus hernia below the heart (open

white arrow). (d) 2D axial view shows small pericardial effusion (yellow arrow). Note breast prosthesis (closed white arrow). Absent left breast (open white arrow). (e) 2D axial view shows right posterior descending coronary artery (open white arrow) and partial calcication of leaflet of aortic valve (closed black arrow). (f) 2D axial view shows mild calcication of part of right posterior descending coronary artery (open black arrow) as well as mild calcication of the circumex artery (closed black arrow).

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