Basal Cell
Carcinoma.
BCC is the most common type of skin cancer.
BCC
BCC accounts for about 70% of skin cancers.
Basal Cell
What is a BCC?
A BCC (Basal Cell Carcinoma) is the most common type of skin cancer. BCC is a very common finding at a skin cancer examination. The cancerous cells originate from the most bottom layer of the epidermis.
BCC has a reputation as being a nuisance rather than being serious. Certainly, BCC is slow growing and only rarely spreads to other parts of the body. However, early diagnosis of BCC is advantageous for these reasons.
- ‘Superficial BCC’, if caught early, can be treated with a cream rather than surgery.
- Nodular BCC, in contrast, requires surgery. However, the extent of surgery that is required will reflect the size of the BCC. Nodular BCC is removed with clear margins. Let’s illustrate the scar size with numbers. Take a small BCC that is just 4mm in diameter. The BCC is cut out with 3mm margins, resulting in a scar that is 24mm long. Now take a 6mm BCC. The scar is now 30mm long. In fact, for every extra 1 mm in diameter, the scar will be 3-4mm longer. This is clearly an issue on the face or scalp where a skin graft or flap may be required. Bear in mind that these figures are conservative, and some types of BCC will need a wider excision.
- BCC can still, albeit it very rarely, spread (metastasize) to other areas of the body.
BCC may need to be cut out with much wider margins that you think.
Who gets them?
BCC is very common in Australia. UV light is of course the major risk factor for BCC (primarily UVB). Intermittent intense exposure to sunlight is important, as well as long term cumulative sun exposure. Use of tanning machines increases risk around 1.5 fold.
Genes are an all-important risk factor for the development of BCC.
Interestingly, emerging evidence suggests that BCC is more common with lower Body Mass Index. Estrogen increases with higher body weight, and estrogen is thought to protect against BCC.
Immunosuppression is a strong risk factor for BCC, with a tenfold increase on the trunk and arms after a solid organ transplant.
Other common risk factors are prior radiotherapy and immunosuppression (though less important than with SCC). Rare risk factors are arsenic exposure and some hereditary conditions such as nevoid basal cell carcinoma syndrome.
What does Basal Cell Carcinoma look like?
There are different types of BCC requiring different treatments. The broad category of BCC may be established clinically prior to excision. However, the pathology report is required to identify any concerning features and to confirm the BCC subtype.
Let’s describe the two main types of BCC:
- Nodular BCC is raised, shiny, maybe pigmented & usually occurs on the face. Nodular BCC needs to be surgically removed.
- Superficial BCC is flat, pink, & is most commonly found on the trunk or limbs. Superficial BCC may be treated with skin cancer cream.
Now let’s look at all the main types of BCC in more detail.
Superficial BCC
Superficial BCC accounts for around 30% of Basal Cell Carcinoma. The condition tends to occur in a younger age group than those affected by other BCC types. Genes play an important role in the development of superficial BCC.
Superficial BCC appears as a pink or red flat lesion with well defined borders. Look for a subtly elevated and/or pearly edge that is best seen on stretching the skin. The lesion may be slightly shiny and/or scaly. Superficial BCC may look similar to an IEC (Bowens disease). A dermatoscope will certainly help distinguish the two with at least 90% accuracy.
Superficial BCC may be treated non-surgically. The most common non-surgical treatment is with Imiquimod (®Aldara) cream.
Gallery of Superficial BCC
Please click on the images for details.
Nodular BCC
Nodular BCC is the most common type of BCC, accounting for around 60% of all Basal Cell Carcinoma. Nodular BCC is found most commonly on the face, head and neck.
A nodular BCC is a raised lesion. In common with other types of BCC, stretching the skin may make the pearly edge clearer. The colour of the lesion is typically pink or red. There may be a central ulcer (the so-called ‘rodent ulcer’) or a central crust. Look for fine blood vessels connecting to a common vessel. These ‘Arborising Vessels’ are much better seen with a dermatoscope. The lesion may be itchy, and tends to bleed with minor scratching.
Gallery of Nodular BCC
Please click on the images for details.
Pigmented BCC
A Pigmented BCC is simply that … a BCC with pigment! This type of BCC accounts for approximately 8% of BCC, and is more common in people with darker skin types. Pigmented BCC is not usually completely pigmented and will have some pink to red areas. The BCC may be flat (‘superficial’) or raised (‘nodular’). Deeply pigmented BCC may look very much like melanoma.
Gallery of Pigmented BCC
Please click on the images for details.
Morphoeic Basal
Morphoeic Basal Cell Carcinoma accounts for 5 to 10% of BCC. The descriptor ‘morphoeic’ refers to the scar-like appearance.
The feature of Morpheic BCC are:
- Ivory color
- poorly defined edges
- feels hard or firm
A morphoeic BCC is harder to treat than other types of BCC.
Gallery of Morphoeic Basal
Please click on the images for details.
Why do they matter?
What is the chance of a BCC re-occurring?
Following full excision of a BCC as confirmed in a pathology report, recurrence rate is under 2%.
The risk of a recurrence is increased with:
- Diameter greater than 20mm on the arms, legs or trunk
- Diameter greater than 10mm on the scalp, forehead, neck or cheeks
- Diameter greater than 6mm on the face (except the forehead and cheeks), hands, feet or genitalia.
- located in the ‘H zone’ of the face – particularly the nose and the fold of skin between the nose and the corners of the mouth (nasolabial fold)
- Immunosuppression
- more aggressive subtypes on the pathology report: infiltrative, micronodular, morphoeic, or perineural extension (into the nerves)
- narrow margins
The surgical margins may need to be wider for a BCC with any of these risk factors.
What is the chance of a new BCC developing?
A person with a previous BCC has a 17-fold increased risk of a new BCC relative to someone who has not had a previous BCC. There is 2-fold increased risk of melanoma, and a 3-fold increased risk of Squamous Cell Carcinoma (SCC).
A new BCC will form in just under half of people diagnosed with a BCC in the last 2 years
More frequent skin cancer examinations will be required.
Treatment for BCC
What is the treatment for BCC?
Treatment depends on the type of BCC. As we’ve said, superficial BCC can be treated with a cream. Aldara is the number one option. Medicare subsidise Aldara treatment provided there is a pathology report confirming the diagnosis.
Nodular BCC requires surgery.
Additional options include curettage and cryotherapy.
BCC Pathology Report
What are the BCC subtypes that are shown on the Pathology Report?
The clinical types of BCC have already been described above: superficial (flat), nodular (raised), pigmented, and Morphoeic (scar-like).
The clinical types may not correlate with the pathology report, and there are types of BCC that can only be determined on the pathology report.
Some types of BCC require extra or more treatment and/or monitoring – so the type of BCC as indicated in the pathology report is important.
BCC pathology reports will often include the term “palisading” and this refers to BCC cells that clump together as blocks or rows along the edge of the BCC.
Perineural invasion is the invasion of nerves by the tumour and, though not common, indicates a more aggressive cancer.
Superficial BCC
Very common type of BCC that corresponds to the pre-excision clinical superficial BCC.
The BCC cells are arranged horizontally in the upper part of the dermis (papillary dermis) and the epidermis. The BCC does not spread deeply. This type of BCC may be treated in a variety of ways.
Solid or Nodular BCC
A common type of BCC where the BCC Cells form in a large clump (or clumps). There may be small spaces called lacunae made up of debris from old cells. Surgical excision with a defined margin is all that is required because this type of BCC is well defined with clear margins – low chance of recurrence.
Cystic BCC
A rare type of BCC where the majority of the BCC is made up of cysts (unlike the small cysts found commonly in a solid BCC). Surgical excision with a defined margin is all that is required.
Basosquamous BCC
BCC with some features of an SCC (Squamous Cell Carcinoma).
Pigmented BCC
BCC that is pigmented. The pigmentation may also be seen clinically (prior to excision). The pigmented BCC is really a description and most pigmented BCC is nodular but may be found in all other types except perhaps morphoeic.
Morphoeic BCC
Morphoeic BCC pathologically corresponds to the clinical feature although the final diagnosis is made by examination of the pathological specimen.
The BCC cells are found in cords or strands within a network of tissue containing collagen (which makes the lesion feel firm). These cords off may be very thin (eg. 2-3 cells in thickness) and so the BCC may spread beyond what can be seen with the naked eye. Therefore, this type of BCC may require additional surgery.
Micronodular BCC
Micronodular BCC consists of multiple small nodules of BCC cells – unlike a solid BCC where there is a single of few larger nodules. The nodules of micronodular BCC may be found deeper in the dermis.
There may be gaps of normal skin in-between the small nodules s of micronodular BCC so it can be difficult to determine the precise edge of the BCC. Therefore this type of BCC may require monitoring or additional surgery and/or wider margins.
Infiltrating BCC
Infiltrating BCC consist of long strands of BCC cells that may be very thin eg just 2-3 cells thick. . They share quite a lot in common with morphoeic BCC except that the infiltrating BCC may extend deeply in the dermis and also extend fairly widely, often surrounded by collagen.
The tumour edges may be difficult to determine because they are less well defined – you can’t see the edge of the BCC as well. This type of BCC may require monitoring or additional surgery with wider margins.
What Terms might I see in a BCC Pathology Report?
The following Terminology might be seen in a BCC Pathology Report.
Palisading
The BCC Cells form in clumps or clusters, and they are a blue colour on the stain.
The BCC cells may be lined up at the edge of the BCC cells almost like bricks. This is referred to as Palisading.
Clefting
Clefting refers to “spaces” that appear (under the microscope) around some areas of BCC.
Basal Cell cancer cells
The Basal Cell Cancer Cells are blue in colour under the standard pathology stain.
Mitoses
The nuclei of the BCC Cells may show mitoses ie. cell division. They reflect the rate of cell division.
Apoptosis
Some of the BCC Cells die – which keeps the BCC in check. These cells appear pink in colour and this programmed cell death is referred to as apoptosis.
Perineural Invasion
The BCC cells may invade the cells – this is called perineural invasion and indicates a more aggressive BCC that may require additional monitoring and/or surgery.
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