Extramammary Paget disease secondary to a transitional cell carcinoma of the bladder.

A 47-year-old male presented with a 4-month history of an erythematous, erosive, and asymptomatic lesion involving the glans and urethral meatus [Figure 1]. He had a history of in situ transitional cell carcinoma of the bladder treated with a radical cysto-prostatectomy 9 years ago. Hematoxylin–eosin stained sections of a biopsy from the plaque showed intraepithelial proliferation of pleomorphic pagetoid cells in a buckshot pattern, involving the full thickness of the epithelium [Figure 2a]. At higher magnification, cells showed pale cytoplasm with large and round nuclei with prominent nucleoli [Figure 2b]. The mitotic index was high. These Paget cells stained positively for epithelial mucins with colloidal iron. Immunohistochemically, the cells expressed positivity for cytokeratin (CK) 7 [Figure 3a], low molecular weight CK [Figure 3b] and p53 while they were negative for S-100, CK-20 [Figure 3c], CDX-2 and gross cystic disease fluid protein (GCDFP-15) [Figure 3d]. The histomorphological and immunohistochemical features, with a history of bladder carcinoma allowed us to make a diagnosis of extramammary Paget’s disease secondary to this malignancy.