Thymic and adenotonsillar enlargement after successful treatment of malignancies

Clinical Significance of Increased FDG Uptake in the Waldeyer Ring and the Nasopharynx Region Identified by PET-CT in Postchemotherapy Follow-up in Patients With Lymphoma: When Should We Perform Biopsy?

PURPOSE

To identify whether fluorodeoxyglucose (FDG) uptake in the Waldeyer ring (WR)/nasopharyngeal (NP) region by positron emission tomography-computed tomography (PET-CT) was physiologic or pathologic in the follow-up of lymphoma patients receiving postchemotherapy treatment.

PATIENTS AND METHODS

We retrospectively examined FDG uptake in the WR/NP region in 534 patients with lymphoma as assessed by PET-CT used for both diagnosis and follow-up.

RESULTS

Forty-nine patients had FDG uptake in the WR/NP region by PET-CT performed after completion of a chemotherapy regimen. Biopsy was performed for 11 of these patients in whom the uptake was considered to be pathologic, and results indicated the presence of reactive follicular hyperplasia. It was considered to be physiologic in 38 patients. PET-CT was repeated after 1 year, and no significant difference was identified between the standardized maximum uptake values (SUV_max; P = .107). The initial diagnosis of 20 patients was made via biopsy performed in the WR/NP region. The SUV_max for the FDG uptake in these patients, asymmetry, SUV_max of the coexisting lymphadenopathies in the neck, and FDG uptake with a counterpart finding by CT were significantly higher than other groups (P = .047, .001, and .005).

CONCLUSION

When deciding whether to resample after treatment completion, it should be taken into account that, in addition to the SUV_max of the lesion, asymmetry, and the SUV_max of the coexisting lymphadenopathy in the neck, a crucial criterion is whether the FDG uptake has a counterpart finding by CT.

Increased 18F-FDG accumulation in the tonsils after chemotherapy for pediatric lymphoma: a common physiological phenomenon

OBJECTIVE

Increased ¹⁸F-fluorodeoxyglucose (FDG) uptake in the tonsils after the completion of chemotherapy in patients with lymphoma may be misdiagnosed as tumor recurrence. This study aimed to investigate the changes in physiological FDG uptake in the tonsils during and after chemotherapy in pediatric patients with lymphoma.

METHODS

A total of 47 FDG-PET/CT scans acquired from 13 pediatric patients with lymphoma (before chemotherapy [preC] = 9; during chemotherapy [durC] = 12; within 1 month after the end of chemotherapy [endC] = 11; and after achieving complete response [postC] = 15) were retrospectively included in this study. FDG uptake in the palatine tonsils was assessed using maximum standardized uptake value (SUV_max). The relative size of the palatine tonsils was calculated as the tonsil-pharyngeal ratio (TPR). Serial changes in the SUV_max and TPR were evaluated.

RESULTS

The mean SUV_max was 3.7 ± 1.7, 2.6 ± 0.7, 2.3 ± 0.8, and 6.2 ± 1.6, at the preC, durC, endC, and postC scans, respectively (p < 0.0001); TPR was 59.0 ± 11.2%, 58.3 ± 9.4%, 54.4 ± 7.9%, and 62.2 ± 12.0% in these groups, respectively, with no significant inter-group differences. TPR and SUV_max showed no correlation.

CONCLUSIONS

Increased physiological FDG uptake in the tonsils is commonly observed after the completion of chemotherapy, even in the absence of reactive hypertrophy.

Cervical lymph node hyperplasia on [(18)F]-fluorodeoxyglucose positron emission tomography/computed tomography scan after treatment of children and adolescents with malignant lymphoma

PURPOSE

To define imaging manifestations and clinical prognosis of cervical lymph node hyperplasia using [(18)F]-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) scanning after treatment of children and adolescents with malignant lymphoma.

METHODS

Children and adolescent patients with malignant lymphoma who had high FDG uptake in their cervical lymph nodes via PET/CT after treatment, which was not due to tumor recurrence or residue, were retrospectively analyzed.

RESULTS

Twenty-seven patients with a median age of 12 years were included; 11 had Hodgkin's disease and 16 had non-Hodgkin's lymphoma. The time from PET/CT scan to completion of therapy was 1-36 months, 85.2% (23/27) of which took place within 12 months. Three patients had confirmed lymph node follicular hyperplasia by biopsy, while all 27 patients achieved disease-free survival during the follow-up period. The maximum standardized uptake values (SUVmax) of cervical lymph nodes were 2.2-16.2 and the maximum short axis ranged from 0.3 to 1.2 cm. Cervical lymph node hyperplasia was noted in neck levels I-V, and neck level II bilaterally had the highest incidence (100%). Bilateral cervical lymph node hyperplasia was symmetrical in terms of both the SUVmax and affected locations. Thymic hyperplasia and nasopharyngeal lymphoid hyperplasia were both observed in 24 patients (88.9%). There was no relationship in terms of the SUVmax between cervical lymph nodes and thymic tissue, cervical nodes or nasopharyngeal lymphoid tissue.

CONCLUSION

Cervical lymph node hyperplasia with high FDG uptake on PET/CT scans found after treating children and adolescents with malignant lymphoma can be benign processes. Awareness of this possibility may help avoid invasive procedures and over-treatment.

Reactive tonsillar enlargement showing strong 18F-FDG uptake during the follow-up of follicular lymphoma

The 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) has become a standard procedure for the diagnosis, staging, and restaging in lymphoma patients. However, a relative high rate of false-positive results has been reported. We report a case of a 40-year-old man with a previous history of a nodal follicular lymphoma, stage IVA, treated with R-CHOP, which showed strong 18F-FDG uptake in the Waldeyer's tonsillar ring during his follow-up, being considered highly suspicious of relapsed lymphoma. A surgical removal of the palatine tonsils and adenoids was performed, which showed reactive follicular hyperplasia. Furthermore, bone marrow biopsy revealed absence of neoplasia. The patient is still in follow-up with no signs of recurrent lymphoma. This case illustrates that, despite the high sensitivity for the detection of recurrent lymphoma, 18F-FDG uptake should be interpreted with great caution and confirmatory studies should be performed before any therapy.