Basal Cell Carcinoma Flashcards
What is BCC?
BCC aka rodent ulcer starts in basal cells lining the bottom of the epidermis, which produces new cells constantly as older cells shed off.
=> very slow growing,
=> locally invasive epidermal skin tumour,
=> rarely metastasizes
=> occurs mainly on areas of chronic sun exposure i.e. the face, head and neck
What are the types of BCC?
There are four types:
• Nodulocystic – most common on face and neck
- Superficial – most common on trunk; may mimic psoriasis, discoid eczema and Bowen’s
- Pigmented - heavily pigmented BCCs can resemble melanoma
- Morphoeic – may resemble a scar; difficult to diagnose
How common is BCC?
BCC is the most common skin cancer => ~ 80% of all skin cancers
80% occur on the head and neck and rest on trunk and legs
Who does BCC affect?
Predominantly fair skinned types
More common at altitude and near the equator
Mostly affects over 50s
Males more than females
What causes BCC?
BCC is caused by sun exposure and DNA damage due to UV light.
DNA repair is able to remove most UV-induced damage but cumulative damage leads to mutations.
=> common mutations in the PTCH1, PTCH2, SMO and SUFU genes predispose to BCC.
Gorlin syndrome/Nevoid basal cell carcinoma syndrome = inherited condition
=> predisposes to recurring non-melanoma skin cancers.
=> born with one mutated allele of the PTCH1 gene leads to an autosomal dominant syndrome of cancer predisposition.
What are the risk factors for BCC?
UV light - chronic sun exposure/tanning beds (greater risk in high altitude/near the equator = increased UV radiation ; severe sunburns)
Genetic factors (PTCH1 gene mutation) Immunosuppression
Fair skin - People who freckle or burn easily or who have very light skin, red or blond hair, or light-colored eyes.
Previous BCC/family hx
Age - BCC takes decades to develop
Radiation therapy
Chronic arsenic exposure
What are the signs & symptoms of BCC?
- Painless lesion
- Slow growing
- Does not heal with medication
- Can occasionally bleed
1. Nodulocystic: => Dome-shaped => Pearly white nodule => Papule => Telangiectasia (small blood vessels form threat-like patterns) => Smooth surface, rolled over edges => Old tumours may present as central ulcerated nodules (rodent ulcer) => Most common type of facial BCC
2. Superficial: => Scaly erythematous plaques => Well-defined raised pearly edges => Most common in younger adults => Most common type on upper trunk and shoulders => Microerosions
- Pigmented:
=> All BCC types can contain flecks of pigment
=> Pearly appearance
=> Heavily pigmented => BCCs can resemble melanoma
4. Morphoeic: => Ill-defined borders => Waxy, scar-like indurated plaque => Wide and deep sub-clinical extension => May infiltrate cutaneous nerve => Usually found in mid-facial sites
What are the differentials for BCC?
1. Nodular: => Intradermal naevus => Sebaceous hyperplasia => Fibrous papule => Molluscum contagiosum => Keratoacanthoma
2. Superficial: => Psoriasis – multiple lesions; bilateral; almost symmetrical; fluctuating in nature => Discoid eczema multiple lesions; diffuse; fluctuating in nature => Bowen’s disease => Actinic keratosis => SCC => Lichen simplex => Seborrhoeic keratosis
- Pigmented:
=> Melanoma - Morphoeic:
=> Scar tissue
=> Localised scleroderma
What are the investigations for BCC?
Clinical diagnosis
Diagnosis and histological subtype confirmed pathologically by biopsy
Clinical examination for lymphadenopathy – no other staging required; CT or MRI indicated in cases where bony involvement suspected or tumour may have invaded major nerves
What is the treatment for BCC?
Surgical:
1. Excision • Gold standard • 4mm margin required • Primary closure, flap or graft • Appropriate for nodular, infiltrative and morphoeic BCCs
- Curettage and cautery (Superficial skin surgery)
• Curette used to scrap off soft material
• Base of tumour destroyed by cauterisation
• Used for small, primary BCCs
• Histology may be difficult to interpret - Mohs’ micrographic surgery
• Excision carried out in stages with each stage checked histologically
• Useful for morphoeic cancers with ill-defined margins, infiltrative, locally recurrent BCCs or sites where it is important to preserve tissue e.g. adjacent to eye, lips and nose
• Very high cure rates - Cryotherapy/cryosurgery
• Small, low-risk lesions on trunks and limbs
• Biopsy would need to be taken first
Non-surgical:
1. Topical treatment Imiquimod 5% cream • Immune response modifying agent • Small, superficial BCCs Fluorouracil 5% cream - cytotoxic agent • Useful for multiple superficial BCCs on trunk and limbs
- Photodynamic therapy (PDT)
• Light therapy in combination with topical photosensitising agent to destroy cancer cells
• Best for superficial BCC, low risks ; avoided if tumour at high risk of recurrance
• Requires 3-4 hour of treatment - Radiotherapy
• Useful for people unsuitable for surgery or margins of excision appear to be incomplete
• Surgery required for reoccurrence
What is the prognosis for BCC?
Excellent prognosis
Metastasis and death are extremely rare
Recurrence rates very low with complete excision, but can be up to 50%
Prognosis for recurrent BCCs is lower
Risk of developing more BCCs increases with previous BCC
What are the complications of BCC?
- Recurrent BCC
Characteristics of recurrent BCC often include:
=> Incomplete excision or narrow margins at primary excision
=> Morphoeic, micronodular, and infiltrative subtypes
=> Location on head and neck
- Advanced BCC
=> Advanced BCCs are large, often neglected tumours.
=> They may be several centimetres in diameter
=> They may be deeply infiltrating into tissues below the skin
=> They are difficult or impossible to treat surgically
- Metastatic BCC
=> Very rare
=> Primary tumour is often large, neglected or recurrent, located on head and neck, with aggressive subtype
=> May have had multiple prior treatments
=> May arise in site exposed to ionising radiation
=> Can be fatal
