Diagnostic Yield of 18F-FDG PET After Lung Transplantation: A Single-center, Retrospective Cohort Study

BACKGROUND

To investigate the diagnostic yield of 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) in lung transplant recipients.

METHODS

A single-center, retrospective cohort study including 234 18F-FDG PET examinations in 199 lung transplant recipients. Indication for PET referral, 18F-FDG PET diagnosis/findings and final clinical diagnosis were classified into 3 groups: malignancy, infection/inflammation not otherwise specified, and chronic lung allograft dysfunction with restrictive allograft syndrome phenotype. Sensitivity/specificity analysis was performed to determine accuracy of 18F-FDG PET in each group.

RESULTS

Sensitivity of 18F-FDG PET for malignancy was 91.4% (95% confidence interval, 82.5%-96.0%) and specificity was 82.3% (95% confidence interval, 74.5%-88.1%). Infection/inflammation not otherwise specified and restrictive allograft syndrome as indication for 18F-FDG PET comprised relatively small groups (14 and 31 cases, respectively). In addition, 18F-FDG PET revealed clinically relevant incidental findings in 15% of cases.

CONCLUSIONS

Referral for 18F-FDG PET after lung transplantation mainly occurred to confirm or rule out malignancy. In this specific setting, 18F-FDG PET has a high diagnostic yield. Accuracy of 18F-FDG PET for other indications is less clear, given small sample sizes. Clinically relevant diagnoses, unrelated to the primary indication for 18F-FDG PET, are found relatively often in this immunocompromised cohort.

An atypical case of a pulmonary mass in an immunocompromised patient

OBJECTIVES

Pulmonary lymphomatoid granulomatosis (PLG) is a rare angiocentric and angiodestructive EBV-associated lymphoproliferative disorder which almost always affects the lungs. PLG is more commonly diagnosed in patients with immunodeficiency and is associated with Epstein-Barr virus (EBV). 'Drug induced PLG' or 'iatrogenic immunodeficiency-associated lymphoproliferative disorder' is a special form of PLG described in patient with inflammatory bowel diseases treated with Azathioprine.

METHODS

We report a case of drug-induced PLG in a 68-year-old patient with Crohn's disease presenting with pain at the right hemithorax, fatigue and shortness of breath with a pulmonary mass.

RESULTS

Although initial diagnostic findings were misleading, an open lung biopsy eventually led to the diagnosis of drug-induced PLG.

CONCLUSION

The diagnosis of PLG is challenging because the disease is rare and the histological features can be very subtle. Correct diagnosis relies on histopathology and immunohistochemical staining and EBV RNA in situ hybridization with sampling of large and different amounts of pathologic tissue in the hands of expert pathologists. In drug-induced PLG specifically, withdrawal of the immunosuppressive agent can lead to disease regression.