Page 624 - Concise Pathology for Exam Preparation ( PDFDrive )

22 The Skin 609

Malignant squamous
cells

Keratin pearl

FIGURE 22.1. Section from a well-differentiated SCC showing atypical cells with abundant
cytoplasm and extracellular keratin pearls (H&E; 2003).

Q. Describe the clinicopathological features of basal cell carcinoma
(BCC).
Ans. BCC arises from the basal layer of the epidermis and constitutes approximately 80%
of all nonmelanoma skin cancers.
• The tumour most often affects individuals aged 40–60 years; is locally aggressive and
rarely metastasizes.
• Advanced lesions may ulcerate and locally invade into the underlying bone and facial
sinuses like a rodent (therefore also called rodent ulcer).
• BCC is commonly located on the face, on the inner aspect of the nose, around
the orbit and on the upper lip (sun-exposed parts of the body), where it appears as
an insidious, painless, nonhealing ulcer or raised nodule containing a central crater.
• In patients with recurrent or deeply infiltrative tumours, involvement of the facial nerve
or branches of the trigeminal nerve may be seen.
Pathogenesis: Risk is related to skin type and the degree of exposure to sunlight, particu-
larly UVB radiation. Mutations in protein patched homolog-1 (PCTH)-1 tumour suppressor
gene are implicated in both sporadic and inherited forms of BCC. P53 mutations are seen
in 40–60% of BCCs.
Genetic syndromes involving BCC:
1. Xeroderma pigmentosa is a rare, autosomal recessive disorder characterized by hyper-
sensitivity to UV radiation. It is due to defects in DNA repair mechanisms and results
in predisposition to cutaneous cancers (eg, BCC, SCC and melanoma).
2. Nevoid basal cell (Gorlin) syndrome is an autosomal dominant disorder associated
with multiple BCCs, odontogenic keratocysts, calcification of falx cerebri and rib
abnormalities.
3. Epidermodysplasia verruciformis is an autosomal recessive disorder characterized by
the development of BCC and SCC from warts.
Types: Different clinicopathological types of BCC exist, each with distinct biologic behaviour:
• Nodular or noduloulcerative BCC
• Constitutes more than 60% of BCCs
• Presents as a well-circumscribed, dome-shaped, pearly nodule with or without
ulceration

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