Bilateral cryptorchidism mimicking external iliac lymphadenopathy in a patient with leg melanoma: role of FDG-PET and ultrasound in management.

Cryptorchidism is the most common congenital anomaly present at birth in males. Spontaneous testicular descent occurs in the majority of patients, typically before 6 months of age. Radiology plays an important role, predominantly in the assessment of the nonpalpable testis, with ultrasound being the most commonly employed modality. Magnetic resonance imaging is however the most accurate modality for the assessment of the nonpalpable testis, particularly with the use of fat suppressed T2 and diffusion weighted sequences. While traditionally treated in infancy, the untreated or occult form can radiologically be mistaken for lymphadenopathy. Fluorodeoxyglucose (FDG) positron emission tomography can play an important role in differentiating cryptorchidism from lymphadenopathy, most commonly in patients with known malignancy, although FDG uptake can be variable. We present a case of bilateral cryptorchidism in an adult male which masqueraded as lymphadenopathy in a patient with lower limb melanoma.