Case Author(s): Sarah E. Reimer, MD and Farrokh Dehdashti, MD , 1/15/99 . Rating: #D3, #Q4

Diagnosis: infected tumor

Brief history:

37 year-old male with history of colon cancer


Axial CT of the pelvis

View main image(ct) in a separate image viewer

View second image(pt). Projection, coronal, axial, and sagittal FDG-PET images.

Full history/Diagnosis is available below

Diagnosis: infected tumor

Full history:

PG is a 37-year-old male with a history of colon cancer, for which he has undergone hemicolectomy. He did well until 1 month prior to this study when he noticed narrowing of his stools. One week prior to this study he began to have intermittent chills.




CT scan demonstrates a fluid collection in the pelvis. Air bubbles are seen in this collection and there is inflammatory stranding of the adjacent fat. FDG-PET scan shows intense tracer activity in the same region as the fluid collection seen on CT.


FDG-PET has been shown to be a successful tumor-imaging tracer. The mechanism of accumulation of FDG into malignant tumors is due to the enhanced rate of glucose utilization by the tumors. However, increased in glucose utilization is not specific to tumors; as, increased FDG uptake has been seen in inflammatory cells such as neutrophils and activated macrophages that are present in areas of acute or chronic inflammation and infection. Recently, FDG has been used for detection of osteomyelitis and infected prostheses.

References: 1. J Nucl Med 1992; 33:1972-80 2. Am J Respir Crit Care Med 1994; 149: 1635-9. 3. Radiology 1998; 206:749-54.


Infected recurrent colorectal tumor was resected.

Major teaching point(s):

FDG can accumulate in both malignant tumors and infection/inflammation

Differential Diagnosis List

1. Malignant tumor. 2. Abscess. 3. Infected tumor.

ACR Codes and Keywords:

References and General Discussion of PET Tumor Imaging Studies (Anatomic field:Gasterointestinal System, Category:Inflammation,Infection)

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Case number: pt021

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