Presentation and causes of pruritus ani

Pruritus ani is a condition characterised by itching of the perianal skin. Persistent scratching often causes lichenification (thickening of skin). In chronic cases, patients may experience more soreness than itch because of fissures, scratching or erosion. Patients often recognise that symptoms are exacerbated by stress. Chronic, excoriated cases may become infected.

Pruritus ani in adults is associated with a dermatosis, most commonly irritant dermatitis, followed by psoriasis, lichen sclerosus and lichen planus. Also consider:

• anal pathology (eg anal fissure, anal skin tags, haemorrhoids, fistulas, warts)
• Crohn disease, perianal intraepithelial neoplasia, extramammary Paget disease (rare)
• worms (eg threadworms) and perianal streptococcal dermatitis, in children
• tinea.

Factors such as insufficient hygiene, faecal incontinence and manner of perianal area wiping can aggravate symptoms but do not cause pruritus ani.

When diagnosing the condition, also consider:

• presence of skin disease on other parts of the body (eg mouth, scalp, nails)
• presence of secondary infection (eg candidal infection)
• aggravating factors (eg sweat, faecal incontinence, irritants or allergens [such as wet wipes], overzealous cleaning).