GPAtlas🧭 When to suspect
Pruritus ani – itching of the perianal skin – is a symptom, not a diagnosis. The clinical task is to find and treat the cause before labelling it idiopathic (no identifiable cause). It is common, affecting up to 5% of people, is around four times more common in men, and typically presents between the fourth and sixth decades.
The itch is characteristically worse at night and after defecation, and is perpetuated by three things: the itch–scratch cycle, minor faecal soiling, and often the very soaps, wipes and creams used to treat it. Most cases (roughly half to nine in ten) are idiopathic, but a secondary cause must always be sought.
The two clinical priorities are therefore: identify and remove the underlying cause and irritants, and never miss an anorectal malignancy or premalignant lichen sclerosus presenting as a persistent itch.
| Category to exclude | Examples |
|---|---|
| Dermatoses | Eczema/dermatitis (irritant or allergic contact), flexural psoriasis, lichen sclerosus, lichen planus, seborrhoeic dermatitis |
| Infections / infestations | Threadworm (pinworm), candida, dermatophyte (tinea), perianal streptococcal dermatitis, anogenital warts, herpes simplex (HSV), sexually transmitted infections (STIs) |
| Anorectal | Haemorrhoids, anal fissure, fistula, skin tags, rectal prolapse, faecal soiling or incontinence |
| Systemic | Diabetes mellitus, thyroid and liver disease, chronic kidney disease, haematological disorders (e.g. lymphoma) |
| Premalignant / malignant | Lichen sclerosus, anal squamous cell carcinoma, extramammary Paget disease |
| Idiopathic / perpetuating | Itch–scratch cycle, overzealous cleaning, fragranced wipes and soaps, dietary irritants, occult faecal leakage |
Source: DermNet
🔒 Sign up free to read the full topic
You're viewing a free preview. Create a free account to unlock the rest.
Sign up free →Sample topics are open to everyone in the Free Sample Bundle.