Basal cell carcinoma (rodent ulcer, BCC)
BCC is the commonest skin cancer. BCCs grow slowly, virtually never metastasize, and
are locally invasive. Some variants can be locally destructive. BCCs present
predominantly in middle-aged Caucasians.
What should I look for?
• Nodulocystic: dome-shaped, pearly papule with telangiectasia coursing over the
surface, more easily identified with dermoscopy, described as ‘arborizing’ vessels which
are in focus when magnified. (Common on the face and neck.) Stretch the skin gently to
accentuate the translucent appearance and borders. Older tumours may present as
ulcerated nodules (rodent ulcers) with smooth rolled pearly edges and telangiectasia
across the surface. remove the loose crust, so you can see the granulating fleshy base.
• Superficial: one or more scaly erythematous plaques (most often on the trunk) with
well-defined raised pearly edges. Stretch the skin gently to make the pearly border of
superficial BCC more obvious, and differentiate from Bowen disease or fungal infection.
• Pigmented: any BCC may contain pigment flecks (seen as ovoid globules under
dermoscopy), but heavily pigmented tumours can simulate melanoma. A pearly
appearance provides clue to the correct diagnosis.
• Morphoeic/infiltrative: waxy, indurated plaque that may resemble a scar. The border
may be difficult to define, even when the skin is stretched.
Squamous cell carcinoma (SCC)
Cutaneous SCCs are the second commonest skin cancer (25% of all keratinocyte
cancers). They usually present in elderly patients on sun- exposed sites and are three
times commoner in men. Prognosis depends on the potential for metastasis, which is
influenced by the anatomical site, pathological features of the tumour (rate of growth,
depth, degree of differentiation), and host immune response.
What should I look for?
• A keratotic nodule or an ulcerated nodule with a granulating base and a rolled
undermined border.
• Induration or ulceration of a solar keratosis or Bowen disease.
• Regional lymphadenopathy.
Keratoacanthoma
Perhaps best regarded as a well-differentiated SCC. These grow rapidly (<6 weeks),
persist for 2–3 months, and then involute over 4–6 months, leaving a depressed scar.
They are usually removed surgically for histological examination.
What should I look for?
• A history of rapid growth over <6 weeks.
• A pinkish symmetrical cup-shaped nodule, 1–2cm in diameter, on sun-damaged hair-
bearing skin, usually the face or neck.
• Smooth rolled edges.
• A central keratin plug.