title: Cryptorchidism as a potential source of misinterpretation in ¹⁸FDG-PET imaging in restaging lymphoma patients.
abstract: OBJECTIVE
  The estimated prevalence of cryptorchidism in young males is close to 2%. In oncological PET/CT studies, it might be difficult to recognize false-positive ¹⁸FDG uptake due to an ectopic testis.
  
  
  METHODS
  In this pilot study, we report on three patients with lymphoma referred for assessment of response to treatment and in whom cryptorchidism was not known at the time of ¹⁸FDG-PET/CT imaging.
  
  
  RESULTS
  In each of these patients, moderate ¹⁸FDG uptake corresponding to an ovoid mass in the inguinal canal was (or could has been) misinterpreted as a lymphoma-involved inguinal lymph node. Clues to avoid misinterpretation are discussed.
  
  
  CONCLUSIONS
  Moderate ¹⁸FDG uptake in ectopic testes represents a potential source of false-positive at initial staging or evaluation of therapeutic response of lymphomas and other malignancies that needs to be recognized.
authors.affiliation: Department of Nuclear Medicine, Saint-Louis Hospital, Paris, France.
authors.forename: David
authors.initials: D
authors.lastname: Groheux
authors.forename: Pierre
authors.initials: P
authors.lastname: Teyton
authors.forename: Laetitia
authors.initials: L
authors.lastname: Vercellino
authors.forename: Alice
authors.initials: A
authors.lastname: Ferretti
authors.forename: Domenico
authors.initials: D
authors.lastname: Rubello
authors.forename: Elif
authors.initials: E
authors.lastname: Hindié
mesh_terms: D000328:Adult; D003456:Cryptorchidism / Q000175:diagnosis* / Q000000981:diagnostic imaging* / Q000473:pathology; D019788:Fluorodeoxyglucose F18 / Q000008:administration & dosage*; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging / Q000473:pathology; D008223:Lymphoma / Q000000981:diagnostic imaging* / Q000473:pathology*; D008297:Male; D064847:Multimodal Imaging / Q000379:methods; D009367:Neoplasm Staging; D010865:Pilot Projects; D049268:Positron-Emission Tomography / Q000379:methods; D011379:Prognosis; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D014057:Tomography, X-Ray Computed / Q000379:methods; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: Cryptorchidism; FDG-PET; Lymphoma; Response evaluation; Retractile testis; Undescended testis