Key distinguishing features of the most common diagnoses
|Normal Skin Surface||No||Yes||No||No||Yes|
Likely:None (skin biopsy or cytology if doubt about the lesion or clinical diagnosis of possible carcinoma).
Possible:Lipid profile, FBC, ESR/CRP, urate, rheumatoid factor/anti-CCP, urinalysis.
Small Print:TFT, skin biopsy, further investigations guided by clinical picture (see below).
- Excision biopsy is the definitive investigation for achieving a diagnosis; cytology from skin scrapings can be used to diagnose BCC.
- Lipid profile: Xanthomata require a full lipid profile to define any underlying hyperlipidaemia.
- Urinalysis: If suspect inflammatory or vasculitic skin lumps, as may reveal proteinuria if associated with systemic and renal disorders.
- FBC and ESR/CRP: ESR/CRP raised in inflammatory disorders and malignancy; may also reveal anaemia of chronic disease or malignancy (including lymphoma).
- Check urate if gouty tophi are clinically likely.
- Rheumatoid factor/anti-CCP: Nodules are usually associated with positive rheumatoid factor.
- TFT: To diagnose Graves’s disease with pretibial myxoedema.
- Skin biopsy: May contribute to a diagnosis of sarcoidosis
- Further investigations according to clinical picture: Some lesions, such as erythema nodosum, may require further investigation to establish the underlying cause; histological confirmation of skin secondaries may similarly require further assessment, although the overall condition of the patient may mean this is a futile exercise.
- Look at the lesion under the magnifying glass – this may reveal suspicious signs such as ulceration or a rolled, pearly edge.
- In uncertain cases which do not require urgent attention, record your findings carefully (including precise dimensions) and review in a month or two.
- Stoical patients may underestimate the significance of a suspicious lesion, particularly if you discover it during a routine examination – if you are referring them for biopsy, impress upon them the need to attend their appointment.
- Establish the patient’s concern, which will usually centre on worries about cosmetic appearance or cancer. This will result in a more functional consultation and a more satisfied patient.
- Night sweats and itching with skin nodules raises the suspicion of lymphoma. Examine lymph nodes, liver and spleen carefully.
- The elderly patient complaining of a lesion in a sun-exposed area which ‘just won’t heal’ may well have a squamous or basal cell carcinoma.
- The appearance of a nodule in a mole is highly significant and requires referral.
- A patient with nodulocystic acne requires referral to a dermatologist for possible treatment with 13-cis-retinoic acid.
- The unwell middle-aged or elderly patient who develops bizarre and widespread skin nodules over a period of a few weeks probably has an underlying carcinoma.