A case of extramammary paget's disease showing that p63 constitutes a useful histochemical marker for the diagnosis

A 78-year-old man had noted red eruption 2 year before in his penis shaft. The skin eruption was diagnosed with herpes simplex and candidiasis. He was treated topically, but his eruption was not improved. He was then referred to us in early April, 2007. Examination showed well-defined erythema with erosion on the inferior surface of the penis shaft. Skin biopsy showed atypical cells with an abundant, pale-staining cytoplasm and round nucleus within the epidermis. Based on positive staining with cytokeratin 7 (CK-7) in the neoplastic cells, we suspected the erythema of extramammary Paget's disease. However, we could not neglect the possibility of pagetoid Bowen's disease, since the neoplastic cells were negative for PAS, and CEA. The total absence of p63 ruled out the possibility of pagetoid Bowen's disease. We surgically removed the skin change under local anesthesia There was no evidence of tumor recurrence or metastasis almost 1 year later.