Other implicated agents are chronic chemical exposure, chronic irritation, and poor hygiene. Etiology Chronic phimosis and poor penile hygiene have been postulated as inciting or contributing events. [emedicine.medscape.com]

Chronic irritation, produced by a perianal fistula and ulcerative colitis, has been implicated as a causative factor. Immunosuppression secondary to HIV disease or due to immunosuppressive medication may be a predisposing factor. [emedicine.medscape.com]