PET•CT-Based Identification of Sarcoidosis in a Patient with Suspected Thoracic Malignancy

Pattern of uptake in the hilar, mediastinal and right scalene lymph nodes was consistent with sarcoidosis.

Partha Ghosh, MD

Case study data provided by Royal Prince Alfred Hospital, Sydney, Australia

 |  2012-10-25

History
A 45-year-old male smoker (20 pack years) presented with right-sided pleuritic chest pain. A chest CT revealed bilateral lung infiltrates as well as right hilar lymph node enlargement. A  fine needle tissue biopsy (FNAB) of the left upper lobe lesion, performed at a regional hospital, revealed adenocarcinoma. FNAB on two attempts of the right upper lobe lesion was not  successful. He was referred for staging with PET•CT. Fludeoxyglucose F 18* (18F FDG) PET•CT was performed on a Biograph™ mCT.

 

*Siemens’ PETNET Solutions is a manufacturer of fludeoxyglucose F 18 injection (18F FDG). Indication and important safety information as approved by the US Food and Drug Administration can be found at the bottom of the page for 18F FDG, adult dose 5-10 mCi, administered by intravenous injection.

 

Diagnosis
The PET•CT study showed markedly glucose-avid foci in both upper lobes of the lung (Fig. 1). SUVmax of the left lobar mass was 18.2; SUVmax of right lobar mass was 25.5. There were additional markedly glucose-avid foci in the hilar and mediastinal lymph nodes on both sides (SUVmax 32.5). The CT showed enlarged hilar nodes as well as lobar masses corresponding to the regions of 18F FDG uptake.

 

Comments
On PET•CT, the pattern of uptake in the hilar, mediastinal and right scalene lymph nodes was consistent with sarcoidosis. Pulmonary infiltrates demonstrated on CT also are commonly associated with sarcoidosis. The diagnostic dilemma was the previous FNAB of the left lobe lesion had suggested adenocarcinoma. The PET/CT findings were suggestive of sarcoidosis, with the possibility of a synchronous primary lung tumor in view of the FNAB findings.

However, the PET•CT findings in isolation were quite typical of sarcoidosis given the clinical history of the patient. In view of the previous FNAB result, suggestive of adenocarcinoma and the PET•CT findings favoring sarcoidosis, it was decided to confirm the diagnosis by surgical excision of the lung lesion. At surgery, the left upper lobe lesion was removed and histopathology revealed necrotizing non-caseating granulomas consistent with sarcoidosis, which confirmed the PET/CT findings.

Improved lesion contrast using ultraHD•PET on Biograph mCT provided exquisite images of the thoracic, mediastinal and portal lymph node lesions, including a 7 mm right scalene node.

 

*Fludeoxyglucose F 18 Injection
INDICATIONS AND USAGE
Fludeoxyglucose F 18 injection (18F FDG) is indicated for positron emission tomography (PET) imaging in the following setting:
Oncology: For assessment of abnormal glucose metabolism to assist in the evaluation of malignancy in patients with known or suspected abnormalities found by other testing modalities, or in patients with an existing diagnosis of cancer.
 

IMPORTANT SAFETY INFORMATION
Radiation Risks
Radiation-emitting products, including fludeoxyglucose F 18 injection, may increase the risk for cancer, especially in pediatric patients. Use the smallest dose necessary for imaging and ensure safe handling to protect the patient and health care worker.
 

Blood Glucose Abnormalities
In the oncology and neurology setting, suboptimal imaging may occur in patients with inadequately regulated blood glucose levels. In these patients, consider medical therapy and laboratory testing to assure at least two days of normoglycemia prior to fludeoxyglucose F18 injection administration.
 

Adverse Reactions
Hypersensitivity reactions with pruritus, edema and rash have been reported; have emergency resuscitation equipment and personnel immediately available.
 

Full Prescribing Information for Fludeoxyglucose F 18 Injection


Fludeoxyglucose F 18 injection is manufactured by Siemens' PETNET Solutions, 810 Innovation Drive, Knoxville, TN 39732

The statements by Siemens customers described herein are based on results that were achieved in the customer's unique setting. Since there is no "typical" hospital and many variables exist (e.g., hospital size, case mix, level of IT adoption) there can be no guarantee that other customers will achieve the same results.