Nodules
Differential Diagnosis
Common Diagnoses
- Sebaceous Cyst
- Lipoma
- Basal Cell Carcinoma (BCC)
- Warts
- Xanthoma
Occasional Diagnoses
- Dermatofibroma (Histiocytoma)
- Squamous Cell Carcinoma
- Nodulocystic Acne
- Kerato-Acanthoma
- Gouty Tophi
- Chondrodermatitis Nodularis Chronica Helicis
- Pyogenic granuloma
- Heberden’s Nodes
- Rheumatoid Nodules
Rare Diagnoses
- Malignant Melanoma (becoming more common in the UK)
- Vasculitic: Erythema Nodosum, Nodular Vasculitis, Polyarteritis Nodosa
- Atypical Infections (e.g. Leprosy, Treponema, Lupus Vulgaris, Fish Tank and Swimming Pool Granuloma, Actinomycosis)
- Lymphoma and Metastatic Secondary Carcinoma
- Sarcoidosis
- Pretibial Myxoedema
Ready Reckoner
Key distinguishing features of the most common diagnoses
| Xanthoma | Sebaceous Cyst | BCC | Wart | Lipoma | |
|---|---|---|---|---|---|
| Reddish-Brown | Yes | No | Yes | No | No |
| Central Punctum | No | Yes | No | No | No |
| Characteristic Distribution | Yes | No | Yes | No | No |
| Normal Skin Surface | No | Yes | No | No | Yes |
| Multiple | Yes | Possible | Possible | Possible | Possible |
Possible Investigations
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.
Top Tips
- 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.
Red Flags
- 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.