Myxoid invasive papillary urothelial carcinoma of the bladder and urethra.

An unusual case of myxoid transitional cell (urothelial) carcinoma occurring in a 75-year-old man is presented. The primary tumour in the bladder, which was treated by partial cystectomy, consisted of areas of conventional high grade invasive (into the lamina propria) papillary urothelial carcinoma with separate myxoid areas. The latter component accounted for 25% of the tumour. Nine months later, the patient presented with haematuria once again, and a tumour was detected in the urethra. This was excised and histological examination showed only myxoid tumour without any overlying dysplasia or obvious epithelial differentiation. The myxoid areas were positive for epithelial markers and negative for all mesenchymal markers. This case highlights an uncommon variety of papillary urothelial carcinoma that invokes a wide differential diagnosis. Immunohistochemistry is essential in making the correct diagnosis.