Infected Sebaceous Cyst
Red flags
Hard, fixed mass +/- suspicious mucosal lesion of aerodigestive tract
Trismus
Spreading cellulitis or rapidly increasing neck swelling
When to involve the ENT registrar
Immediately: Suspicion of deep neck space infection ie adverse signs and sepsis
Soon: Large abscess requiring formal surgical drainage in operating theatre
Assessment and recognition
The diagnosis is clinical and comes with experience.
Cysts are firm but mobile (see Fig. 1 below)
They are in the skin itself, rather than deep to it
They transilluminate a little at best
There is frequently a yellow/white central punctum; a foul cheesy material may discharge from this
They are usually painless unless infected; If infected, they will be cellulitic and very painful
The presence of trismus or other adverse signs suggests something more complex than an infected sebaceous cyst. Infected cysts are very painful and can sometimes even cause pyrexia, but they do not cause trismus, dysphagia or other aerodigestive tract signs.
Ensure you perform a full head and neck as well as general medical examination.
Figure 1. A non-infected sebaceous cyst in a typical area, the nape of the neck.
Differential diagnosis
IMMEDIATE & OVERNIGHT Management
Infected cysts should be drained as soon as possible whereas non-infected cysts – even large ones – should not as there is a risk of introducing infection. If bothersome, ENT surgeons will excise non-infected cysts electively.
If clinical proven to be infected sebaceous cysts, those on:
the lobule of the ear
on the bony scalp around the ear
around the hairline (nape) of the neck
can be drained with a wide gauge needle and a 10ml syringe. (There are no important structures in the lobule, otherwise ENT surgeons would have to do all the ear piercings!).
Aspiration brings significant relief – please consider it if the patient is not due to see an ENT surgeon within a few hours. Local anaesthetic can be instilled but usually this is as painful as needle aspiration. Be wary of aspirating large neck swellings in the anterior triangles.
Patients can be discharged on oral antibiotics to cover skin pathogens. Arrange follow-up in the ENT emergency clinic in 2-3 days.
Figure 2. Infected sebaceous cyst of the nape of the neck, with central punctum discharging cheesy or pus-like material. If examination revealed this to be non-pulsatile and confined to the skin, immediate aspiration would bring significant relief.
Further management
Once the infection has settled, the patient may choose to have an elective excision of the cyst remnant, as infection will recur.
Page last reviewed: 1 December 2022