Imaging in primary penile cancer: current status and future directions

Penile cancer is a rare neoplasm in the developed world. Clinical assessment often results in inaccurate staging and radiological techniques have a key role in staging and postoperative assessment. Magnetic resonance imaging (MRI) depicts penile anatomy in detail and is the most accurate technique for local staging and postoperative follow-up. MRI and ultrasound (US), although helpful for assessment of lymph nodes, are not reliable enough for accurate nodal staging. US-guided fine needle aspiration cytology (FNAC), however, remains a valuable tool to confirm metastases in suspicious inguinal nodes. Lymphoscintigraphy with dynamic sentinel node biopsy (DSNB) is a promising technique used to predict occult lymph node metastases. Novel imaging techniques such as positron emission tomography/computed tomography (PET-CT) and nanoparticle enhanced MRI have high sensitivity and specificity for lymph node metastases but their availability is limited and clinical utility is not fully established. The radiologist needs to be familiar with the normal penile anatomy, imaging appearances of pre- and post-treatment penile cancer, and the advantages and limitations of the available imaging techniques. This review highlights the above points and presents a systematic approach to make the best use of imaging in the management of patients with penile cancer.