Urinary bladder urothelial carcinoma with concurrent plasmacytoid and micropapillary differentiations: A report of two cases with an emphasis on serum carbohydrate antigen 19-9

We report two cases of urinary bladder urothelial carcinoma (UC). In both, histological examination of a transurethral resection specimen of the bladder tumor revealed UC with plasmacytoid and micropapillary differentiations. In Case 1, residual plasmacytoid UC deeply invaded the extravesical fat tissue of the radical cystectomy specimen, and metastatic carcinoma was found in almost all the dissected lymph nodes. Despite adjuvant chemotherapy and radiotherapy, the patient died 25 months postdiagnosis. Elevated serum carbohydrate antigen 19-9 (CA19-9) returned to near normal levels after radical cystectomy, but they increased shortly before death. In Case 2, no residual carcinoma was found in the radical cystectomy specimen or lymph nodes. Postoperative serum CA19-9 was maintained at normal levels, and the patient remains alive without recurrence or metastasis. Although plasmacytoid and micropapillary UC are known aggressive variants of UC, plasmacytoid UC may be more aggressive. Serum CA19-9 could serve as a useful biomarker to monitor progression of plasmacytoid UC.