{"doi":"10.1002/ajh.26073","title":"Testicular <scp>FDG‐PET</scp>/<scp>CT</scp> uptake threshold in aggressive lymphomas","abstract":"Primary testicular lymphoma (PTL) and testicular involvement of systemic lymphoma (secondary testicular lymphoma, STL) are uncommon.1, 2 Most testicular lymphomas are aggressive B-cell lymphomas with the most common histologic type being diffuse large B-cell lymphoma (DLBCL) and most common cell of origin being activated B-cell like phenotypes.1 Primary testicular lymphoma is generally ascribed to cases where testis are the primary or main site of lymphoma involvement, but has also been defined more restrictively as testicular involvement without lymph node or bone marrow involvement.2 Lymphomas with testicular involvement portend a high risk of extranodal relapse, including CNS relapse and evaluation often includes a diagnostic lumbar puncture while treatment is typically intensified to include CNS prophylactic therapy such as intrathecal chemotherapy or systemic methotrexate.1, 2 Determination of testicular involvement at diagnosis is therefore essential for appropriate evaluation and management of this aggressive disease. Note, F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) is a standard imaging modality to stage aggressive lymphoma. There is often visible uptake in the testes that raises concern with clinicians, but there is a lack of consensus data to determine whether the uptake is physiologic or pathologic. Physiologic testicular avidity on FDG-PET/CT has been described in a Japanese study, which reported a mean standard uptake value (SUV) of 2.44 ± 0.45 (maximum SUV not reported) for all age groups based on FDG-PET/CT of 203 men3 who underwent FDG-PET/CT for cancer diagnosis or cancer screening with no history of malignancy in the testis and no abnormal findings in the testis on CT images. While there are reports on normal testicular uptake on FDG-PET/CT, no clear SUV thresholds to raise suspicion for testicular involvement by lymphoma have been established. An Australian retrospective study reviewed 3781 male patients with a diagnosis of lymphoma without a clinical suspicion of testicular involvement. Twelve had abnormal testicular or scrotal FDG above that of background activity as determined visually and quantitatively by PET-accredited nuclear medicine physicians. Seven of these twelve patients were subsequently diagnosed with testicular involvement by lymphoma, of which six were aggressive lymphomas including DLBCL and Burkitt lymphoma with mean testicular SUVmax 10.2 (range 3.3–17.5).4 This suggests a population of patients with unsuspected STL may be identified on FDG-PET/CT. However, no particular FDG cut off level was defined in that study. A testicular SUV threshold to alert for lymphoma involvement would be clinically relevant and help guide management. In this study, we compared testicular FDG avidity in patients with known testicular involvement by lymphoma with physiologic testicular FDG avidity from patients without known lymphoma. Records of patients from Mayo Clinic diagnosed with PTL or STL from 2002–2015 enrolled in the University of Iowa/Mayo Clinic Lymphoma Specialized Programs of Research Excellence (SPORE P50 CA97274) Molecular Epidemiology Resource5 were reviewed, yielding 10 patients with testicular lymphoma with intact testes at the time of staging FDG-PET/CT. Normal physiologic testicular avidity by FDG-PET/CT was determined from a subset analysis of our previously published normal value study of 350 male patients6 including 70 patients, 10 patients per decade ages 18 to 90 years, who received FDG-PET/CT from 2013–2018 prior to treatment for non-lymphoma indications (solitary pulmonary nodule, lung carcinoma, head & neck squamous cell carcinoma, gastrointestinal carcinomas, metastatic melanoma), without known hematologic malignancy, testicular pathology, or history of testicular infection/surgery by medical chart review. All FDG-PET/CT exams utilized a standard oncologic protocol with three-dimensional lutetium yttrium orthosilicate detectors (128x128 ma","journal":"American Journal of Hematology","year":2020,"id":112084,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":4,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9578,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2020-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":530808,"name":"Hidong Kim","orcid":"0000-0002-5587-5432","position":1,"is_corresponding":false},{"id":530809,"name":"Laura Harper","orcid":"0000-0001-5835-6139","position":2,"is_corresponding":false},{"id":396925,"name":"Thomas M. Habermann","orcid":"0000-0003-3532-9132","position":3,"is_corresponding":false},{"id":371973,"name":"Grzegorz S. Nowakowski","orcid":"0000-0002-6955-9393","position":4,"is_corresponding":false},{"id":488010,"name":"Carrie A. Thompson","orcid":"0000-0002-4518-2309","position":5,"is_corresponding":false},{"id":530810,"name":"Patrick B. Johnston","orcid":"0000-0002-3212-3510","position":6,"is_corresponding":false},{"id":11125,"name":"Thomas E. Witzig","orcid":"0000-0002-4215-6500","position":7,"is_corresponding":false},{"id":531367,"name":"Cristine Allmer","orcid":null,"position":8,"is_corresponding":false},{"id":239734,"name":"Matthew J. Maurer","orcid":"0000-0002-1867-0526","position":9,"is_corresponding":false},{"id":302818,"name":"James R. Cerhan","orcid":"0000-0002-7482-178X","position":10,"is_corresponding":false},{"id":530811,"name":"Jason R. Young","orcid":"0000-0001-5351-8266","position":11,"is_corresponding":false},{"id":491007,"name":"Gita Thanarajasingam","orcid":"0000-0003-2144-5415","position":12,"is_corresponding":false},{"id":530807,"name":"Alexandra Higgins","orcid":"0000-0001-6626-0700","position":0,"is_corresponding":true}],"reference_count":6,"raw_metadata":null,"created_at":"2026-07-18T23:13:09.353152Z","pmid":"33338288","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}