eSurgery

This is written with the aim of helping my medical students and doctors in training go through my thought process in the outpatient clinic. This list is not meant to be all comprehensive but rather a practical guide in coming to a diagnosis quickly.

1. Duration – has this lump been there for some time and growing slowly (most likely epidermal/pilar cyst)
2. If the lump is of recent onset and is painful – consider if that could be an inflammed epidermal cyst or abscess
3. Lymph node – especially in back of scalp eg occipital lymph node. An US can be helpful if the lump is large – to see if the normal lymph node architecture is present or absent. In case of the latter, consider US-guided FNAC
4. Have a look : if subcutaneous – epidermal cyst. But also to consider lipoma especially at back of scalp. The pilar/epidermal cyst usually has a punctum – but that may not be easily seen(although when you inject LA into the lump, you can sometimes see a bit squirting out) Because of the thick skin, it can be difficult to differentiate a lipoma from a cyst.
If on the skin – consider – skin cancer eg melanoma, BCC or SCC. (I can recall a sad case where a young woman in her 20s presented with a large nodular melanoma on the scalp with satellite nodules – this was discovered by her hairdresser )
5. Other rarer causes – osteoma (bony tumours of the scalp), other soft tissue tumour, tricholemmal cyst

Management:
Offer excision under local anaesthesia – to remove the lump. Best to use an artery to dissect bluntly in the plane around the cyst wall if possible. The Local anaesthesia is also good at helping in creating a plane between the cyst and the surrounding tissue(a bit of hydrodissection). Be careful when injecting in LA or when you incise a cyst that is tense with local anaesthesia – the LA may just squirt out (together with some sebaecous material that may not be smelling all that good…think months of accummulated dirt under the armpit) I always send the lump for histology. If lipoma, it is important to exclude the rarer spindle cell variant which can be more likely to turn to a liposarcoma. Make sure too to remove all the pseudopodia of the lipoma to reduce the risk of recurrence.