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CECAL SESSILE SERRATED ADENOMA (PET-CT)
Authored By: Farrokh Dehdashti and Andrew Homb.
Patient: 74 year old female
History:

74 year-old woman with recurrent hypercalcemia and a presumed paraneoplastic syndrome.

 

Figure 1

Figure 2

Figure 3

Figure 4

 

Findings, differential, and Recommendations?

 

CT Images

 

Figure 5

 

Next step in management?

 

Figure 6

Image Size:[small][as-submitted]

Multimedia: 245486_1_submitted.avi
Rotating PET avi

Fig. 2
Coronal PET

Fig. 3
Axial PET-CT

Fig. 4
MPR PET

Fig. 5
Axial CT

Fig. 6
Colonoscopy images
Image Size:[small][as-submitted]

Findings:

PET-CT:

 

RADIOPHARMACEUTICAL: 14.8 mCi F-18 Fluorodeoxyglucose (FDG) i.v.

 

Focal moderate to markedly increased FDG uptake in the proximal cecum at the junction of the appendix and cecum. This is a nonspecific finding and can be seen in benign and malignant colonic lesions.  Colonscopy is recommended.

 

CT:

 

No definite abnormality noted in the proximal cecum at the junction of the appendix and the cecum.

 

Colonscopy:

 

Medium-sized mass in the cecum, right at the appendiceal orifice measuring 1 cm in length and 1.2 cm in diameter.  See the colonoscopy pictures.

DDx:

Single focus of increased FDG bowel uptake:

 

Malignant

 

Metastatsis

 

Primary colon cancer

 

Premalignant

 

adenomas

 

Benign

 

Hyperplastic Polyps

 

Infection/Inflammation

Diagnosis: Sessile serrated adenoma
General Discussion:

Full History:

 

74 year-old woman with recurrent hypercalcemia and a presumed paraneoplastic syndrome.  The patient's also has traumatic paraplegia, severe vertebral compression fractures, osteoporosis and hypothyroidism. The study is requested for diagnosis of an occult malignancy.

 

Discussion: Focal Bowel Uptake on PET-CT

 

1 to 3 % of patients who undergo PET-CT demonstrate a focus of increased bowel uptake (uptake greater than liver). 

 

A retrospective study was performed by Kei et al. evaluating 2,250 consecutive patients undergoing PET-CT for malignant disease.  They identified 22 patients with 25 foci of increased bowel uptake (greater than liver) that had a susequent follow-up procedure performed (surgery or endoscopy).  21 of these lesions corresponded to an endoscopic or surgical abnormality (positive predictive value, 84%).  7 lesions were malignant, 13 premalignant, and 1 benign.  11 additional non-FDG avid lesions were demonstrated by endoscopy; however, all of these lesions were less than 1 cm and likely below the resolution of PET.  There was no statisically significant difference in maximum SUV between the malignant, premalignant, and benign lesions.  12 of 21 PET positive lesions had a CT correlate, particularly if it was in a nondependent portion of the bowel.

 

Conclusions:

 

"The incidental finding of focal FDG uptake in bowel justifies further investigation of these foci and should not be dismissed as physiologic uptake.  Premalignant lesions, such as adenoma, are often found, and early treatment may prevent the development of carcinoma."

 

FDG PET has difficult picking up lesions less than 1 cm due to resolution issues

 

Differentiation between malignant, premalignant, and benign lesions can not be made on the basis of maximum SUV

 

Many FDG positive lesions also demonstrate a CT correlate, particularly in the lesion is in a non-dependent portion of bowel.    

References: Kei at al.  "Incidental Finding of Focal FDG Uptake in the Bowel During PET/CT: CT Features and Correlation With Histopathologic Results"  AJR 2010; 194: W401-W406.
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Additional Details:

Case Number: 245486Owner(s): Farrokh Dehdashti and Andrew HombLast Updated: 12-07-2011
Anatomy: Gastrointestinal (GI)   Pathology: Neoplasm
Modality: CT, PETAccess Level: Readable by all users, writable by NucMed Certifiers
Keywords: ptnm

Case has been viewed 22 times.
Certified by Farrokh Dehdashti on 11-21-2011

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