Malignant melanoma metastatic to the ovary: presentation and radiological characteristics.

Cutaneous melanomas rarely metastasize to the ovary; however, we have recently encountered three cases which have proved a diagnostic dilemma. All presented with a pelvic mass and a past history of cutaneous melanoma but both ultrasound examination and CT scanning proved inconclusive and neither was able to accurately characterize the lesions. Magnetic resonance imaging (MRI) was able to demonstrate the presence of melanin in one of the ovarian lesions as peripheral high signal change on T1-weighted images. The two lesions without melanin failed to show this feature. MRI may therefore be useful in the diagnosis of ovarian melanoma but only if melanin is present.