A 53-year-old man presented with recurrent squamous cell carcinoma, and dysplasia of the scrotum and penis. Risk factors included psoralen and ultraviolet radiation therapy for psoriasis, and x-ray therapy for primary lymphoma of the groin. Three different human papillomavirus types were documented using the polymerase chain reaction in distinct anatomical areas. The scrotal carcinoma was associated with human papillomavirus type 18, while regions of dysplasia contained either type 18, 16 or 6/11. Diagnosis of squamous dysplasia and carcinoma of the scrotum in men with psoriasis is complicated by chronic active inflammation, and molecular biological methods may be necessary to detect human papillomavirus infected cells.