F-18 fluorodeoxyglucose positron emission tomography in pulmonary cryptococcoma.

Area of Science:

• Medical imaging and diagnostics
• Nuclear medicine
• Infectious diseases

Background:

• Fluorodeoxyglucose (FDG) positron emission tomography (PET) is a valuable tool for differentiating pulmonary nodules and distinguishing infection from malignancy.
• Interpretation pitfalls can arise, particularly in regions with a high prevalence of granulomatous infections or in immunocompromised patients.
• Accurate differential diagnosis is crucial for appropriate patient management.

Observation:

• A patient presented with a nodular mass on chest radiography and computed tomographic (CT) scanning.
• CT findings, including air bronchograms within the mass and perihilar infiltration, suggested consolidated infection or bronchioloalveolar carcinoma.
• The FDG PET scan showed intermediate-high glucose uptake (SUV 3.8-4.0), aiding in the exclusion of bronchioloalveolar carcinoma, which typically exhibits normal or mildly increased FDG uptake.

Findings:

• The intermediate-high FDG uptake on PET scan was inconsistent with typical bronchioloalveolar carcinoma.
• The imaging findings ultimately led to the diagnosis of cryptococcoma.
• CT and FDG PET imaging played complementary roles in reaching the final diagnosis.

Implications:

• FDG PET interpretation requires careful consideration of clinical context and local disease prevalence.
• Complementary use of CT and FDG PET enhances diagnostic accuracy for pulmonary nodules.
• This case highlights the importance of recognizing potential pitfalls in FDG PET interpretation for infectious versus malignant pulmonary lesions.