Pruritis and Dermatology

Dr Matthew Harries Hope Hospital, Salford

Powerpoint File

Pruritus ani is defined as an itch localised to the anus and perianal skin. It is more common in middle aged men and can be associated with most forms of anal disease or skin conditions involving the perianal area. The common factor linking most cases of pruritus ani is faecal contamination of the perianal skin resulting in irritation and subsequent itch. Faecal contamination may result from problems in cleaning the area; such as simple obesity, frequent defaecation or anatomical factors (e.g. "funnel anus"). It may also occur with anal leakage that may be secondary to local factors (e.g. haemorrhoids, fissures) or due to primary anal sphincter dysfunction.

The initial assessment should concentrate on identifying an underlying cause for the pruritus. Bacterial and fungal infections are important to exclude. Pinworm infestations are particularly common in children and can be identified using the "Sellotape test". Primary skin conditions including psoriasis, eczema, lichen planus and lichen sclerosus may also present with itching. Allergic contact dermatitis may result from applications of topical medicaments applied in an attempt to treat the initial irritation. In a number of cases, however, no underlying cause will be identified.

Management begins with advice about keeping the anus clean by washing after defaecation; irritants should be avoided and loose underwear worn. A mild topical corticosteroid may be soothing and help settle any inflammation present. Specific treatment may be required depending on the underlying cause identified.

Pruritus ani is a common problem in general medical practice. By paying attention to personal hygiene and by treating any underlying cause the symptoms of this often distressing condition can be minimised.

Further reading

Jones DJ. Pruritus ani. ABC of colorectal diseases. BMJ 1992; 305: 575-577.

Verbov J. Pruritus ani and its management - a study and reappraisal. Clin Exp Dermatol 1984; 9: 46-52.

Bastawrous A, Chaudhry V. Specific pruritus ani. Semin Colon Rectal Surg 2003; 14: 203-212.