Basal cell carcinoma is a slow-growing type of skin cancer that rarely metastasizes but can be locally aggressive. It arises from the basal cell layer of the epidermis or hair follicles, resembling cells in the basal epidermal layer. Risk factors include chronic sun exposure, light pigmentation, genetic conditions like xeroderma pigmentosum, radiation exposure, and skin injuries. It is caused by mutations in the PTCH1 tumor suppressor gene, dysregulating the hedgehog signaling pathway. Basal cell carcinoma typically appears as pearly papules or nodules on sun-exposed skin, often with prominent blood vessels visible within the lesions.

1. Basal cell carcinoma
❑Slow growing tumors
❑Rarely metastasize
❑Locally aggressive (Rodent ulcer)

2. Basal cell carcinoma
Arises from the basal cell layers of the epidermis
or, from the follicular epithelium
(Resembles cells in the basal layer of the
epidermis)

3. Basal cell carcinoma
Predisposing factors
➢ Chronic exposure to ultraviolet light
➢ Lightly pigmented people
➢ Xeroderma pigmentosum (DNA repair defect)
➢ X-ray exposure
➢ Tattoos
➢ Skin injury

4. Xeroderma Pigmentosum

5. Pathogenesis
• Mutations in PTCH1 (Tumor suppressor gene)
• Excessive activation of Hedgehog signalling
pathway
PTCH1 (Protein patched homolog 1)

6. C/F
• Pearly papules often containing prominent, dilated
subepidermal blood vessels (telengiectasias)
• May appear as nodules with central crater
-Sides of the crater are surfaced by telengiectactic vessels.
• Occurs in sun-exposed areas (Sites):
a) Inner canthus of the eye, upper lip
b) Very general rule of thumb is that BBCs favor upper lip
and higher.

7. Basal cell carcinoma
Pearly papule showing
telengiectasia Nodule with central crater

8. Morphology
Two patterns are seen.
A) Nodular lesion: Cords and islands of basophilic cells with
hyperchromatic nuclei.
The cells forming the periphery of the tumor
cell islands tend to be arranged radially with their long axes
in approximately parallel alignment (palisading)
The stroma shrinks away from the
epithelial tumor nests creating clefts or retraction artifacts

9. Basal cell carcinoma

10. Morphology
B) Multifocal superficial growths: Originating from the epidermis
and extending over several square centimeters (This makes it
difficult to get free margins after surgery)