Bladder Metastasis of Extramammary Paget’s Disease: A Case Report

Extramammary Paget’s disease (EMPD) is a cutaneous malignancy which is characterized by growth of Paget’s cells in anatomical sites other than breast skin. The areas of predilection for the disease are usually vulva, axilla, and the perianal region. Bladder metastasis is very rare, because metastasis most commonly occurs in lymph nodes. Here we show a rare case of bladder metastasis of EMPD of the vulva. A 77-year-old man was referred to our hospital with erosion of the penis. Surgical resection was performed as a treatment under the diagnosis of EMPD. One year later, an abdominal CT showed a left hydronephrosis and thickening of the bladder wall, where cystoscopy revealed irregular mucosa on the left side of the bladder wall. Pathologic examination with immunohistochemical stains of bladder mucosa showed bladder metastasis of Paget’s disease of the vulva. Occasionally, the Paget phenomenon is observed from the external urethral orifice to the vulva in transitional cell carcinoma of bladder. Paget phenomenon and EMPD are histochemically and symptomatically very similar, and differentiation between the two is essential. CK20 and GCDFP-15 staining are used for such differentiation, and pathologic examinations of immunohistochemical stains effectively diagnose EMPD.