18F-FDG-PET/CT in the surveillance of patients with lymphoma: detection of asymptomatic recurrences

18FDG-PET/CT Specificity for the Detection of Lymphoma Recurrence in the Tonsils

Objective

In patients with a history of lymphoma who demonstrate palatine tonsil uptake on posttreatment PET/CT (positron emission tomography/computed tomography), tonsillectomy is often performed to evaluate for lymphoma recurrence. However, predictive clinical and imaging factors for true tonsil recurrence in this setting are not well established; this will be explored herein.

Study Design

Retrospective case series.

Setting

Patients treated at a tertiary medical center from January 2008 to May 2020.

Methods

Chart review was performed on all patients with a history of treated lymphoma in clinical remission who presented for evaluation of abnormal PET/CT imaging findings and subsequently underwent tonsillectomy.

Results

Among 15 patients who met inclusion criteria, 14 had benign findings on surgical pathology, yielding a false-positive rate of 93%. The patient with malignancy was identified on biopsy after inconclusive surgical pathology and is the only documented case of recurrence in this specific patient population throughout the literature. The patient presented with B symptoms, irregularly shaped tonsils, increased lymph node activity on PET/CT, and uptrending bilateral tonsil activity but with one of the lowest maximum standardized uptake values of the cohort. The singular distinguishing feature for the patient with recurrent disease was a prior tonsil biopsy suspicious for recurrence, which prompted the otolaryngology referral.

Conclusion

PET/CT lacks specificity in identifying lymphoma recurrence in the oropharynx. Clinical and radiographic features that were previously considered concerning for recurrence are most likely not indicative of malignancy in this patient population. Our findings call into question whether tonsillectomy should be routinely performed in this patient population.

Malaria masquerading as relapse of Hodgkin's lymphoma on contrast enhanced (18)F-fluorodeoxyglucose positron emission tomography/computed tomography: A diagnostic dilemma

(18)Flurodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) is nowadays routinely used in management of lymphoma patients. We here present a case of Hodgkin's lymphoma which showed (18)F-FDG avid splenomegaly on PET/CT done for clinically suspected relapse. Further evaluation by peripheral smear examination revealed malaria. The patient was then started on anti-malarial medications and follow-up PET/CT revealed resolution of hypermetabolic splenomegaly. This report highlights that in endemic regions malaria can cause (18)F-FDG avid splenomegaly and might mimic relapse of lymphoma.

Fluoro-deoxy-glucose positron emission tomography/computed tomography in lymphoma: A pictorial essay

F-18 fluoro-deoxy-glucose (FDG) positron emission tomography/computed tomography (PET/CT) has emerged as a powerful imaging modality in the field of oncology. F-18 FDG PET/CT is now an established tool in the management of lymphoma. This has been shown to be useful in staging, detection of bone marrow involvement (BMI), early response assessment and end of therapy response assessment in lymphoma. Interpretation of F-18 FDG PET/CT in lymphoma is carried out by various qualitative response assessment criteria. London criteria are used for interpretation of interim PET/CT and International Harmonization Project (IHP) criteria are used to interpret PET/CT done after the end of chemotherapy. Quantitative analysis is also found to be useful in assessment of response early after two cycles of chemotherapy in patients with diffuse large B cell lymphoma (DLBCL). This pictorial essay provides few images describing the FDG avidity of lymphoma, patterns of bone marrow uptake and their relevance in predicting BMI, role of staging PET/CT, quantitative analysis in response assessment, example images of response according to London criteria and IHP criteria. Few pitfalls in imaging of lymphoma with PET/CT are also discussed in the images legend.