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


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 (18)F-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).


CONCLUSIONS
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.
Department of Hematology, Yokohama Municipal Citizen's Hospital, Yokohama, Japan.
Hitomi
H
Nakayama
Department of Hematology, Yokohama Municipal Citizen's Hospital, Yokohama, Japan.
Yoshinobu
Y
Aisa
Department of Hematology, Yokohama Municipal Citizen's Hospital, Yokohama, Japan.
Chisako
C
Ito
Department of Hematology, Yokohama Municipal Citizen's Hospital, Yokohama, Japan.
Kengo
K
Shimazaki
Department of Radiology, Yokohama Municipal Citizen's Hospital, Yokohama, Japan.
Yasushi
Y
Katsumata
Department of Pathology, Yokohama Municipal Citizen's Hospital, Yokohama, Japan.
Hiroyuki
H
Hayashi
Department of Hematology, Yokohama Municipal Citizen's Hospital, Yokohama, Japan. Electronic address: n-tomo@eurus.dti.ne.jp.
Tomonori
T
Nakazato
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003362:Cost-Benefit Analysis; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008223:Lymphoma / Q000000981:diagnostic imaging* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography / Q000191:economics; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000191:economics; D055815:Young Adult
Complete remission; Histology; Malignant lymphoma; PET-CT; Second primary malignancy