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Why does this young man have a painful lump in his armpit?


The patient

‘I just need some antibiotics, doc.' I've heard that before, especially in the middle of a busy duty surgery. On this occasion though, he was probably right. He was complaining of a painful lump in his left armpit, which had started a few days ago and was becoming increasingly uncomfortable. Otherwise, he was well, and on no medication. The only entry on his summary screen was for troublesome acne, which had been treated with antibiotics for a few months about three years ago.

First instinct

This sounded like a straightforward mild axillary abscess. And it looked like that, too – although it was rather easier to feel than to see.

My brief examination revealed a walnut-sized tender swelling with a little surrounding erythema in a 24-year-old man who otherwise looked well. The only other obvious finding was some nodulocystic acne on his chest.

Differential diagnosis

• Abscess

• Acne

• Pilonidal abscess

• Diabetes mellitus

• Hidradenitis suppurativa

• Crohn's disease.

I really didn't need to think too hard about alternative diagnoses – this just seemed like a straightforward presentation of an abscess, needing a course of antibiotics and instructions to attend A&E if it reached the point where incision and drainage looked necessary.

A very inflamed acne cyst was a possibility, given his past history and the evidence of co-existent acne. And pilonidal sinuses can lead to abscesses, particularly in hairy areas – though I've only come across these in the finger webs and the natal cleft.

Of course, anyone presenting with abscesses – especially if recurrent – could be a case of undiagnosed diabetes. But he volunteered none of the relevant classical symptoms.

Hidradenitis suppurativa was another possibility, but not one I dwelt on as virtually all cases I've ever seen were in women.

A long shot, especially with recurrent boils, is Crohn's disease – but the pathology here is usually perianal, and he had no gastrointestinal symptoms at all.

The hidden clue

When I checked for any allergies, he replied: ‘None I know of, doc – they usually give me flucloxacillin.'

So – this was a recurrent problem, a fact he hadn't volunteered and I hadn't elicited, though there was a big clue in his conviction that he'd need antibiotics.

And the notes hadn't helped much, as the previous consultations were buried deep in ‘journal', with no summary entry for ‘recurrent abscesses' or similar.

Getting on the right track

A negative urinalysis – excluding diabetes – and a quick re-examination later and I was reassessing my diagnosis, because he had a number of nodules, scars and sinuses in his axillae – and a few in his groins, too.

So he had hidradenitis suppurativa. And he did need antibiotics – but long term rather than a short course, which might help his acne, too.

Dr Keith Hopcroft is a GP in Laindon, Essex

Hidradenitis suppurativa Hidradenitis suppurativa


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