Primary malignant melanoma of the urethra in a patient with rheumatoid arthritis treated with methotrexate.

We report a case of a 79-year-old woman with urinary incontinence who presented at a urogynaecology appointment. Her medical history included rheumatoid arthritis (RA) treated with methotrexate (MXT) for 22 years. A polypoidal lesion was protruding from the meatus urethrae. The histoimmunocytology confirmed a primary superficial spreading malignant melanoma. The tumour was extensively excised, but 8 months later, due to a lymphatic nodal swelling, a positron emission tomography/CT was performed showing a process suspicious of malignant melanoma and multiple distant metastasis. The subsequent treatment was palliative and 1 year later, the patient died. The aetiology of malignant melanomas in the urethra is poorly understood. There is consistent evidence that RA is associated with a number of cancers, but it remains controversial whether this risk is increased with MXT. This case emphasises the importance of gynaecological examination even in patients with only weak symptoms from the pelvic region, especially in patients undergoing immunosuppressive treatment. © BMJ Publishing Group Limited 2019. No commercial re-use. See rights and permissions. Published by BMJ.