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17 Lipomas oftheColon
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a(i) a(ii)
a(iii) a(iv)
237
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
inltration 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 reects 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withdrawn, the tumour will spring back to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].
17 Lipomas oftheColon
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239
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 >40mm.
• 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
>30mm, symptoms may the occur. There are two
treatment options: endoscopic removal of lesions
<30mm, 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 denitive 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 Signicance, andtheRole
ofOpportunistic Screening
JoelH.Bortz
18
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 denitely 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 45years or older. It has
the added ability to detect extracolonic lesions in
the abdomen and pelvis. These lesions are classied as either clinically important or unimportant
[4]. The denition of a clinically important nding is one that necessitates further diagnostic
studies or medical/surgical follow-up. ECFs were
identied in 63% of patients in a study by Yee
etal. [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 benet 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 benet of detecting
important or signicant 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 signicant
ndings (usually <10%) in most CTC studies in
asymptomatic individuals. In a study by Pickhardt
etal. [9], the prevalence of polyps (≥10mm) 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 signicantly without inuencing the nal outcome.
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023
J. H. Bortz et al. (eds.), CT Colonography for Radiographers,
https://doi.org/10.1007/978-3-031-30866-6_18
241
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J. H. Bortz
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 signicant ndings,
and (2) the additional cost of the work-up of the
ECFs was $28 per CTC examination [10]. ECFs
were identied in 69% of patients in a study of
681 asymptomatic patients: 10% of the ECFs
were highly signicant 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: 120kVp and 50–75mAs
• No IV contrast media
• Automatic reconstruction of 5mm contiguous
CT slices.
– Advantage of 5mm 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 5mm contiguous images is
performed in all cases. There are several advantages in making the images 5mm 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 identied, 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 identied in a
2010 study of 2277 patients undergoing
CTC screening [14]. Extracolonic detections
increased with age. Macari etal. [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 calcication
• AI: articial 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: Hounseld unit
• ML: machine learning
• ROI: region of interest
• TBS: trabecular bone score
18 Extracolonic Findings, Their Clinical Signicance, andtheRole ofOpportunistic Screening
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18.2 Benets ofVisualising
Extracolonic Organs and Tissues
Signicant pathology may be identied 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 benets 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 benets 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 identied 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 identied in 3.5
cases/1000 whereas colon cancer is identied 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 65years 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 30mm (3cm) 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 >50mm.
18.2.1 Negative Aspects ofECFs
The negative aspects of extracolonic ndings
include:
(a) added diagnostic cost
(b) time consuming to evaluate these ndings,
thus adding to overall reporting time
(c) patients may be subjected to increased anxi-
ety and risks. Especially following biopsies,
or exploratory surgery for what turns out subsequently to be an insignicant nding [4].
18.3 Clinical Importance ofECFs:
Low, Moderate, andHigh
It is useful to divide ECFs in asymptomatic
patients into three categories: low, moderate, and
high importance. Benign lesions, such as kidney
18.4 Classication ofECFs
Zalis etal. [21] classied 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
• signicant importance (= medically important)
ECFs may be either clinically insignicant or
signicant, depending on whether additional workup is required. For example, if a pleural effusion is
visualised it would be classied as E3: moderate
clinical importance. Visualisation of a simple renal
cyst would be classied as E2: low clinical importance. Examples of ECFs for each level of clinical
importance are presented in Table18.1. A revised
classication of ECFs is a work in progress and
should be published within the next few months.
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Table 18.1
E classication
b
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 calcication
Calcied 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 ≥10mm
Vasculature: aortic aneurysms >50mm
Lung: non- uniformly calcied pulmonary nodule ≥10mm
Irreducible inguinal hernia containing large bowel
pneumothorax, pneumoperitoneum must
be communicated to the referring
physician/ health practitioner
a
It must be remembered that an extracolonic evaluation is limited by lack of IV contrast and the low-dose CT technique
b
Adapted from Zalis etal. [21]
ab
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18.5 Examples ofECF Images
It is important that every organ and bony structure is carefully evaluated on every CTC image
[22]. The E-classication in Table18.1 is used to
present examples in each classication. As evident in these examples, the majority are classied
as being of low clinical importance (E2). Only a
c
few are classied as being of signicant clinical
importance (E4).
18.5.1 E1: Not ofClinical 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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J. H. Bortz
d(i)
e
d(ii)
f
g
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 calcication. (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)
ab
ef
18 Extracolonic Findings, Their Clinical Signicance, andtheRole ofOpportunistic 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.
cd
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 calcication of leaflet of aortic valve (closed black arrow). (f) 2D axial view
shows mild calcication of part of right posterior
descending coronary artery (open black arrow) as well as
mild calcication of the circumex artery (closed black
arrow).
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