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BENING MUSCULOSKELETAL UPTAKE ON FDG-PET
Authored By: Farrokh Dehdashti and Archana Kantawala.
Patient: 59 year old female
History: 59 year old female with a new diagnosis of endometrial adenocarcinoma. She was diagnosed with breast cancer 10 years prior to the diagnosis of endometrial cancer for which she underwent mastectomy followed by chemotherapy. She is now being worked up for endometrial cancer.
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Multimedia: 311620_1_submitted.pptx
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Findings:

FDG-PET findings -

1. Moderately increased FDG uptake within the vaginal cuff. The differential diagnosis for this uptake includes either residual disease or infectious/inflammatory disease.

2.Focal markedly increased FDG uptake posteriorly in the right acetabular roof without a CT correlate is of unclear etiology; although, metastatic disease cannot be entirely excluded.

Plain film findings- Normal right hip.

Bone scan findings - Intense uptake in the acetabular roof on the right side. This focus is worrisome for metastatic disease.

MR findings- Round focal marrow infiltrating lesion within the posterior wall of the right acetabulum which correlates to the abnormal bone scan and PET findings. Concern is for osseous metastatic disease from breast cancer or endometrial cancer.

 

DDx: Increased FDG uptake as well as increased radiotracer uptake on the bone scan may be related to inflammatory changes. However given the focal nature of the uptkae especially on the FDG-PET study, metastatic marrow disease should be considered in the differential diagnosis.
Diagnosis:

The patient underwent a core biopsy of the right hip. Microscopic examination of the tissue sample demonstrated reactive fibrosis.Cytokeratin immunohistochemistry conformed the absence of malignant cells.

It was agreed that the FDG uptake was due to reactive fibrosis. Restaging FDG PET-CT study done 6 months after the initial PET study showed interval resolution of the metabolic activity.

General Discussion:

A wide spectrum of benign musculoskeletal disorders are associated with focal FDG uptake and may be incidentally detected in cancer patients.

Conditions such as tendinopathy and bursitis fall into this category.Activated inflammatory cells exhibit increased expression of glucose transporters. In addition, the affinity of glucose transporters for deoxyglucose is apparently increased by cytokines and growth factors

It is necesary to keep in mind that FDG is a nonspecific radiotracer and certain benign conditons will demostrate increased metabolic activity on the study. The images should be interpreted keeping in mind the normal physiologic variations in distribution.

In this case however, the focal nature of FDG uptake was atypical and especially in a patient with history of two cancers, was concerning for metastatic disease.

References:

spectrum of Focal Benign Musculoskeletalat PET/CT of the Shoulder and Pelvis 

 

 

18F-FDG Uptake Vladimir Sopov, Hanna Bernstine, Dorit Stern,Nikolay Yefremov,Jacob Sosna, David Groshar

 

 

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Additional Details:

Case Number: 311620Owner(s): Farrokh Dehdashti and Archana KantawalaLast Updated: 12-07-2011
Anatomy: Skeletal System   Pathology: Non-Infectious Inflammatory Disease
Modality: Conventional Radiograph, MR, PETAccess Level: Readable by all users, writable by NucMed Certifiers
Keywords: ptnm

Case has been viewed 13 times.
Certified by Farrokh Dehdashti on 11-09-2011

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