Unilateral testicular relapse of abdominal non-Hodgkin lymphoma detected by FDG-PET

Moderately intense FDG uptake in the testis is regarded as a normal variant, especially in younger patients [1, 2]. In one study [1], physiological testicular uptake was found to be approximately 6.0 and 3.6 times higher than muscle and blood levels, respectively. This uptake of FDG into the normal testis declines with age [1]. However, intense uptake, especially if unilateral, can signify disease involvement. A 7-year-old boy presented with a 3-month history of fever, pain and an abdominal mass. Abdominal CT revealed multiple hypodense nodules in both kidneys and a large, irregular intraperitoneal mass infiltrating the mesentery, engulfing some small-bowel loops and causing compression and displacement of the urinary bladder. CTguided biopsy of the mass revealed it to be non-Hodgkin lymphoma (NHL). He was treated with eight cycles of chemotherapy over 6 months. One month after the last cycle, CT demonstrated a small residual soft-tissue mass in the pelvic cavity infiltrating adjacent bowel loops as well as the superolateral aspect of the urinary bladder. There was near-total regression of the lymphomatous deposits in both kidneys with a residual small nodule observed in the posterior cortex of the right kidney. Whole-body FDG-PET (Fig. 1) performed 1 month after the last cycle of chemotherapy demonstrated uptake in the mesenteric mass and the residual nodule in the right kidney,