Anal Swelling
Because of embarrassment on the part of the patient, this may well present as a ‘while I’m here’ symptom. The temptation to make a diagnosis without examination should be resisted – some of the causes (such as perianal abscesses) require urgent attention and others may, rarely, provide something of a surprise (e.g. fistulae, carcinoma).
Differential diagnosis
Common Diagnoses
- Prolapsed Pile
- Perianal Haematoma
- Skin Tags
- Perianal Abscess
- Rectal Prolapse
Occasional Diagnoses
- Warts
- Sebaceous Cyst
- Sentinel Pile
- Infected Pilonidal Sinus
Rare Diagnoses
- Hidradenitis
- Anal Fistula
- Carcinoma
Ready reckoner
Key distinguishing features of the most common diagnoses
| Prolapsed Pile | Perianal Haematoma | Skin Tags | Perianal Abscess | Rectal Prolapse | |
|---|---|---|---|---|---|
| Painful | Possible | Yes | No | Yes | No |
| Intermittent | Possible | No | No | No | Possible |
| Constipated | Possible | Possible | No | Possible | Possible |
| Long History | Possible | No | Yes | No | Possible |
| Rectal Bleeding | Possible | Possible | No | Possible | No |
Possible investigations
- In most cases, investigation will be unnecessary. The only exceptions are warts (in which case referral to the local GUM clinic may be required to screen for sexually transmitted disease) and possible carcinoma (in which case biopsy will be performed in secondary care). Also, any suspicion of Crohn’s disease causing perianal disease would be investigated in hospital in the usual way.
Top Tips
- This is one of those situations in which a brief history can be taken while the patient is undressing, or during the examination. Atypically for primary care, it’s the examination, rather than the history, which usually provides the definitive diagnosis.
- If a discharge, as well as a lump, is mentioned by the patient, then abscesses, warts, prolapses and fistulae top the list of differentials.
- The patient with an anal swelling who has obvious difficulty walking into the consulting room has either an abscess, a large perianal haematoma or strangulated prolapsed piles.
Red Flags
- Recurrent or multiple fistulae suggest Crohn’s disease.
- If a prolapsed pile is very swollen and painful, it is probably strangulated, and so requires urgent surgical attention.
- A persistent, ulcerating anal swelling, especially in the middle-aged or elderly, requires urgent biopsy to exclude carcinoma.