Extramammary Paget's disease of the glans penis secondary to urethral recurrence of bladder carcinoma after radical cystectomy: A case report

INTRODUCTION: Extramammary Paget's disease of the vulva secondary to urothelial carcinoma is rare. It is important to determine whether extramammary Paget's disease is primary or secondary, because the appropriate treatment strategies differ. We report a case of penile extramammary Paget's disease secondary to urothelial carcinoma recurrence. CASE PRESENTATION: A 75‐year‐old man who was diagnosed with bladder carcinoma and received urethra‐sparing radical cystectomy 5 years ago presented with erythema and red spots in the glans penis. Immunostaining (cytokeratin 7 and cytokeratin 20) of skin biopsy specimens suggested a secondary extramammary Paget's disease that originated from the urothelial carcinoma. Under urethroscopy, urethral recurrence was also suspected. A total penectomy was performed, and a final diagnosis of urothelial carcinoma recurrence and secondary extramammary Paget's disease of the glans penis were established. CONCLUSION: Using immunostaining, the differential diagnosis between primary and secondary extramammary Paget's disease is more accurate. Secondary extramammary Paget's disease should be considered when a skin lesion is present on the penis of patients with urothelial carcinoma.