Primary malignant melanoma of the bladder collides with high-grade non-invasive urothelial papillary carcinoma: A case report

The present study reported a case of primary malignant melanoma of the bladder colliding with high-grade non-invasive urothelial papillary carcinoma with clinical, pathologic and immunohistochemical analysis, and reviewed the relevant literature. A 74-year-old male presented with hematuria; B ultrasound and computed tomography revealed a solid mass in the bladder and transurethral resection of the bladder lesion was performed. Microscopically, the tumors were composed of morphologically diverse malignant melanomas (95%) and high-grade non-invasive urothelial papillary carcinoma (5%), with no closely related or transitional regions. Immunohistochemistry indicated that malignant melanoma cells expressed HMB45, Melan-A and S-100, whereas they did not express any epithelial markers. The urothelial carcinomas expressed broad-spectrum cytokeratin and GATA3, and were negative for melanoma markers. The diagnosis of collision tumor between primary malignant melanoma of bladder and high-grade non-invasive urothelial papillary carcinoma depends on clinical and pathological examinations; this pathology is prone to recurrence and metastasis and has a poor prognosis.