A patient with newly diagnosed, early-stage bulky classic Hodgkin lymphoma (cHL) had a false-positive result from positron emission tomography (PET) with 18F-labeled fluorodeoxyglucose (18F-FDG), leading to repeated tests and additional unnecessary workup. The details of the case report were recently published in the Journal of Oncology Practice.1

18F-FDG-PET is an effective tool for the assessment of malignant lymphomas; however, it is nonspecific in differentiating malignancy from inflammation or infection,” the study authors wrote.

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The patient described in the report was a man aged 34 years with early-stage bulky cHL who had completed 6 cycles of standard-dose doxorubicin, bleomycin, vinblastine, and dacarbazine, resulting in the complete resolution of the hilar lymph nodes and decreased size of an 18F-FDG–avid mediastinal mass, as determined by PET/CT. The residual mass was treated with consolidative radiotherapy.

At 8 weeks after radiotherapy, the residual mass was still present, as determined by PET/CT. At 10 weeks after radiotherapy, the patient was asymptomatic, had a performance status of zero, and a physical examination that was described as “unremarkable.” The residual mass was confirmed via CT, and a core-needle biopsy was performed, revealing no sign of large atypical CD30+ cells. Another biopsy revealed still no evidence of malignancy.

At 21 weeks and 32 weeks after radiotherapy, PET/CT scans continued to suggest a residual mass. At 38 weeks, an excisional open-thoracic biopsy was done and revealed necrosis, chronic inflammation, and histiocytes, but no large atypical CD30+ cells.

“Despite the concerning 18F-FDG uptake in the residual mass, it continued to decrease in size,” the study authors wrote. They reasoned that a decrease in size may favor active observation in an otherwise asymptomatic patient and that the decision to obtain a biopsy should be recommended if the patient has clinical symptoms or the 18F-FDG uptake and tumor size increases after therapy.

Reference

Cramer FM, Chuang HH, Miranda RN, and Lee HJ. False-positive positron emission tomography after combined-modality induction therapy in a patient with newly diagnosed early-stage bulky classic Hodgkin lymphoma. J Oncol Pract. doi: 10.1200/JOP.19.00258