Extracutaneous melanomas: a primer for the radiologist

OBJECTIVE: The purpose of this article is to provide a comprehensive review of the imaging features of extracutaneous melanomas. CONCLUSION: Extracutaneous melanomas are clinically and biologically distinct from their more common cutaneous counterpart with higher frequency of metastatic disease and poorer overall prognosis. Complete surgical excision is the treatment of choice whenever possible; systemic therapy in the form of conventional chemotherapeutic agents as well as novel targeted agents is used for advanced/ metastatic disease. Multiple imaging modalities including US, CT, MRI and FDG-PET/CT play important roles in the evaluation of the primary tumour, assessment of metastatic disease and monitoring response to treatment. Radiologists should be aware of the typical imaging manifestations of extracutaneous melanoma, the distinct patterns of metastatic involvement as well as treatment response and toxicities associated with newer molecular targeted and immunotherapies to optimally contribute to patient management. TEACHING POINTS: • Mucosal melanoma is clinically and biologically distinct from cutaneous melanoma. • Mucosal melanoma has a higher rate of metastatic disease than the cutaneous subtype. • Imaging is helpful in assessment of disease and response to treatment.