Cancer, pigmentation, hair and nails
Skin cancer
Approach to a suspicious lesion
History: evolution, bleeding, itch/pain, previous skin cancer, sun exposure, immunosuppression and family history. Examine the entire skin when appropriate and regional nodes. Use dermoscopy if trained; photograph and measure with consent.
- Australia and New Zealand have the highest reported melanoma incidence and mortality in the world1.
- Actinic keratoses are marker lesions of sun damage; field treatment (e.g. topical creams) or lesion-directed treatment such as cryotherapy are options4.
- Melanoma risk factors: many naevi, atypical (dysplastic) naevi, a personal history of melanoma (about 10 times the population risk, so lifelong surveillance), family history (only 5-10% are truly familial; some carry CDKN2A mutations), fair skin, red hair and freckling (MC1R variants), poor tanning, sunburn and sunbeds5.
- About a quarter of melanomas arise in an existing naevus; most arise in previously normal skin. Giant congenital naevi (over 20 cm) carry a lifetime melanoma risk of up to about 6%5.
- Benign mimics of melanoma5: seborrhoeic keratosis (waxy, 'stuck on', keratin plugs on the surface); blue naevus (stable blue-grey, often on the backs of hands and feet); haemangioma (blanches with a glass slide); subungual haematoma (maroon, with a clear band as the nail grows out); dermatofibroma (firm, dimples when squeezed from the sides); pigmented BCC (pearly papular border).
Melanoma warning features
ABCDE: asymmetry, border irregularity, colour variation, diameter/change and evolution. Also consider the “ugly duckling,” a new or changing lesion, nodular EFG pattern (elevated, firm, growing) and amelanotic melanoma.
- Mnemonic, BITCHES (suspect malignancy in melanoma): Bleeds, Irregular / Itch, Tender, Colour change, Halo, Enlargement, Satellite lesions.
- DermNet: ABCDE = Asymmetry, Border irregularity, Colour variation, Different (formerly diameter), Evolving; nodular melanoma EFG = Elevated, Firm, Growing. Not all melanomas follow ABCD; the Glasgow 7-point checklist is an alternative1. Suspicious melanoma generally requires prompt complete excision biopsy with a narrow clinical margin where feasible; avoid destructive treatment.
- Radial versus vertical growth: most melanomas first spread outwards within the epidermis (radial growth), when excision is usually curative; once they grow downwards (vertical growth) they can metastasise. Nodular melanoma skips the radial phase and invades early5.
Clinical types of melanoma5.
| Type | Typical site and patient | Behaviour |
|---|---|---|
| Superficial spreading | Commonest in fair skin; back in men, back and lower legs in women; age 40-50 | Usually present 1-7 years before diagnosis; irregular, notched edge, mixed colours |
| Lentigo maligna melanoma | Chronically sun-exposed cheek and temple; around age 70 | Long in situ phase (5-20 years) before invading |
| Nodular | Any site; age 40-50 | Rapid; no outward phase; blue-black or red-blue nodule that may ulcerate |
| Acral lentiginous | Palms, soles, nail beds, mucosa; around age 60 | Commonest type in darker skin and East Asian people |
- About 70% of early melanomas are noticed because they grow or change colour; bleeding, ulceration and pain are late signs5.
- Darker-skinned people get melanoma 10-20 times less often, but more often on acral and mucosal sites and at a later stage, with worse outcomes5.
Basal cell carcinoma
Common, usually slow-growing and rarely metastatic but locally destructive. Nodular lesions may be pearly with telangiectasia or ulceration; superficial lesions are scaly; morphoeic lesions resemble scar and have ill-defined margins. Treatment depends on site, subtype, size and patient factors and may include excision, Mohs surgery or selected non-surgical therapies.
- Histological subtypes include nodular, superficial and infiltrative (morphoeic); pathology reports deep and lateral margins and incomplete excision warrants further surgery2. Mohs micrographic surgery is used for high-risk sites/subtypes2.
- Mechanism: BCC arises from basal epidermal cells and usually carries mutations in the hedgehog pathway (PTCH1, SMO)5.
- Subtype pitfalls: superficial BCC (scaly red plaques on the trunk) is easily mistaken for nummular eczema or psoriasis; pigmented BCC can mimic melanoma; morphoeic and micronodular BCC are the most invasive, with indistinct borders that hide spread beyond what is visible5.
- Metastasis is extremely rare (under 0.1%), but central face, ear and scalp lesions, large tumours and aggressive subtypes recur more. After a BCC or SCC, up to 40% develop another skin cancer within 5 years5.
Squamous cell carcinoma
Often a rapidly growing, tender, firm or hyperkeratotic lesion on sun-exposed skin. Risk rises with immunosuppression, chronic wounds and high-risk lip/ear sites. Bowen disease is SCC in situ. Prompt biopsy/excision and risk stratification are required; assess regional nodes in high-risk disease.
- High-risk cutaneous SCC features include diameter 2 cm or more and location on the ear, lip vermilion, central face, hands, feet or genitalia3. Bowen disease = intraepidermal SCC3.
- How SCC looks: an ulcerated red nodule or superficial erosion (often the lower lip), or a warty papule or plaque; surface telangiectasia is uncommon and the edge may be ill defined or fixed5.
- Metastatic risk: overall about 0.3-5%, mostly to regional nodes, but around 13% on the lower lip and 11% on the ear, higher in scars, chronic ulcers and genital or mucosal sites, and up to about 30% for recurrent tumours. Large, poorly differentiated, deep tumours with perineural invasion and tumours in immunosuppressed people (e.g. transplant recipients) behave aggressively5.
- Precursors and mimics: actinic keratoses and actinic cheilitis are premalignant (estimated progression 0.25-20%). Keratoacanthoma is a dome-shaped nodule with a central keratin-filled crater that grows fast and may regress, but is hard to tell from SCC5.
Management and follow-up
Histology determines diagnosis, Breslow thickness and margins. Definitive excision margins, sentinel-node assessment, imaging and systemic therapy are specialist/stage dependent. Counsel on sun protection, self-examination and follow-up for recurrence and additional primary cancers.
- Melanoma excision margins (Australian Clinical Practice Guidelines 2018 as quoted by DermNet): in situ 5 mm; under 1 mm 10 mm; 1-2 mm 10-20 mm; 2-4 mm 10-20 mm; over 4 mm 20 mm1.
- Sentinel node biopsy is recommended in Australia/NZ for melanoma thicker than 1 mm, or over 0.75 mm with other high-risk features; it helps staging and adjuvant therapy decisions but does not improve survival1. Breslow thickness is the strongest predictor of outcome1.
- Other important prognostic factors are ulceration, nodal involvement, distant metastases and raised serum LDH; Clark level is no longer used. Scalp, hand, foot and mucosal melanomas do worse than forearm and leg melanomas, and older men tend to present later with thicker tumours5.
- Most skin cancers are driven by cumulative UV exposure that starts in childhood; early treatment of precancerous and in situ lesions lowers the later risk of invasive disease5.
Notes
References
- DermNet: Melanoma
- DermNet: Basal cell carcinoma
- DermNet: Cutaneous squamous cell carcinoma
- DermNet: Actinic keratosis
- Longo DL, Fauci AS, Kasper DL, Hauser SL, Jameson JL, Loscalzo J, editors. Harrison's Principles of Internal Medicine. 18th ed. New York: McGraw-Hill; 2012. Chapter 87, Cancer of the skin.
Last updated from Sen’s notes on 22 October 2026.