Importance of Histologic Verification of Positive Positron Emission Tomography/Computed Tomography Findings in the Follow-Up of Patients With Malignant Lymphoma

We evaluated histologically verified after therapy positron emission tomography/computed tomography (PET/CT)-positive lesions in the follow-up of 190 patients with malignant lymphoma in first complete remission. Among 32 patients with histologically verified disease, 10 exhibited relapse of lymphoma, 11 had second primary malignancies, and 11 had benign/normal lesions. The symptomatic PET/CT-positive patients had a significantly shorter overall survival than the asymptomatic PET/CT-positive patients. The histologic diagnosis should be considered in posttherapy PET/CT-positive lymphoma patients. Introduction: Posttherapy positron emission tomography/computed tomography (PET/CT) scanning in patients with malignant lymphoma remains controversial. We aimed to evaluate the utility of achieving histologic verification of positive PET/CT findings in the follow-up of patients with malignant lymphoma. Patients and Methods: A total of 771 PET/CT scans were performed as posttherapy follow-up in 190 lymphoma patients who had experienced a complete remission at our institution. Fifty-two patients (27.3%) had F-18-fludeoxyglucose-positive lesions on posttherapy PET/CT, and a histologic diagnosis was carried out in 32 cases (16.8%). Ten patients (5.2%) exhibited relapse of lymphoma. Twelve lesions in 11 patients (5.8%) were proven to be second primary malignancies (SPM). Eleven patients (5.8%) were proven to have benign or normal tissue lesions. Results: Among the 32 histologically verified PET/CT-positive patients, the symptomatic PET/CT-positive patients (n = 10; 4 SPM, 6 lymphoma relapse) had a significantly shorter overall survival rate than the asymptomatic PET/CT-positive patients (n = 22; 7 SPM, 4 lymphoma relapse, 11 benign/normal tissue lesions) (2-year overall survival, 48.2% vs. 100%, respectively; P < .001). Conclusion: This study emphasizes that the histologic diagnosis should be confirmed in posttherapy PET/CT-positive patients via biopsy before adjusting the treatment regimen as a result of the high false-positive rate, including unexpected SPM or benign/normal tissue lesions. (C) 2015 Elsevier Inc. All rights reserved.