Group 2

Members: Ashleigh, Jessica,Cindy
e-Facilitator: Sophie

HEY GUYS REMEMBER TO IN-TEXT REFERENCE!

a. Discuss how the basement membrane is formed and the role of the basal layer in its formation - here we can look at the histological structure etc.
b. Discuss the etiology and epidemology of Skin and Basal Cell Carcinomas
c. Outline the pathology of the disease and its clinical significance in the dental practice



SKIN AND BASAL CELL CARCINOMAS


Contents

  • What is Skin Cell and Basal Cell Carcinoma?
  • Clinical Signifcance and Types of BCCs
  • Etiology and Epidemology
  • Diagnosis and Prognosis
  • Treatment



What is Skin Cell and Basal Cell Carcinoma (BCC)?

Basal cell carcinoma is the most prevalent but least dangerous cancer of the skin, and also the most prevalent cancer of the head and neck (Regezi, Sciubba & Jordan 2002). These usually localised lesions are most often encountered in older male patients on non-hair-bearing areas, presumably as a result of cumulative sun exposure (Regezi, Sciubba & Jordan 2002). It is a type of non-melanoma skin cancer (NMSC) and is composed of basal cells which derive from the squamous epithelium making up the outer layer of the skin (Ibsen & Phelan 2004).

Prevalence of BCCs

The 2002 National Non-Melanoma Skin Cancer Study estimated that:
  • around 256,000 people were diagnosed with BCC in 2002
  • 96 per cent of people with BCC were aged 40 years or older

Based on the age-specific incidence rates in 2002 and subsequent population change, it is estimated that 295,000 Australians will be diagnosed and treated for BCC in 2008.
In 2006, there were 410 deaths from non-melanoma skin cancer in Australia.

Who gets Skin Cancer?

Tortora and Derrickson (2006) states that three common forms of skin cancer exists including malignant melanomas being the least common out of the three; squamous cell carcinomas accounting for approximately 20% of all skin cancers and the majority of skin cancers being basal cell carcinomas which account for more than 75% of all skin malignancies. Factors which increase skin cancer prevalence include increasing age, in addition to gender with skin cancer being almost twice as common in males.

Geographically, the basal cell carcinoma tumour is found worldwide, but with striking geographical variation, with incidence decreasing with increasing distance from the equator. Basal cell carcinomas are more common in regions with high levels of sunlight.

Predisposing Factors

The most important predisposing factor in the development of basal cell carcinoma is the exposure to ultraviolet radiation (UVB) in sunlight. Chronic exposure to sunlight is associated with premature aging, blunting of the immunological responses of the skin to environmental antigens and the development of premalignant and malignant neoplasms.

However, there are also important genetic contributions to the development of basal cell carcinoma. Risk factors relating to exposure and susceptibility to sunlight include: fair skin, Northern European ancestry, childhood freckling and number of past sunburns. The type, timing, and quantity of sun exposure associated with an increased risk in the development of BCC have not yet been fully defined.

With basal cell carcinoma it is currently believed that it is childhood sun exposure rather than cumulative sun exposure that is the main aetiological factor in the development of BCC in later life. In addition, short periods of intense sun exposure are thought to be more dangerous than chronic exposure to a similar total dose.

Other predisposing factors with basal cell carcinoma include:
  • Ionising radiation;
  • Chemical carcinogens such as arsenic, chronic immunosuppression (incidence of squamous cell carcinoma much greater than that of BCC); and
  • Rare genetic conditions such as xeroderma pigmentosa and basal cell naevus syndromes.

The genetic bases for these syndromes have played an important role in the investigation of the molecular pathogenesis of BCC, with the discovery of mutations in the tumour suppressor region of the PTCH gene on chromosome 9 being found in the inherited and sporadic cases of basal cell carcinoma.





Clinical Significance and Types of BCCs

According to the Australian College of Dermatologists (2004), the clinical manifestations of the BCC tumor are highly variable and may appear in several forms, as outlined in Table 1.0 below. Wells (2008) describes how the carcinoma most commonly begins as a shiny papule, enlarges slowly, and, after a few months or years, displays a shiny, pearl-coloured border with prominent engorged vessels (telangiectases) on the surface and a central ulcer. At this stage, recurrent crusting or bleeding is not unusual, but patients may alternately crust and heal (Wells 2008). Often, this unjustifiably decreases patients' and physicians' concern about the importance of the lesion (Wells 2008).

While most BCCs develop on sun-exposed areas such as the head, neck, trunk, and legs, it can potentially appear anywhere on the body (American Academy of Dermatology 2009).

Why Basal Cell Carcinoma is Serious
Basal cell cancer rarely metastasizes or travels in the bloodstream, but still has the potential to infiltrate the surrounding area and destroy surrounding tissue, causing permanent disfigurement (American Academy of Dermatology 2009). It is especially concerning when a BCC tumor develops near an organ such as an eye, ear, or nose, or grows near a nerve, as complications such as loss of an eye can arise if the cancer invades (American Academy of Dermatology 2009).

external image mole1.jpg
NODULAR AND NODULAR-ULCERATIVE BCCs
These are most common. They start as round, hard, red or red-grey pearly bumps, which might continue to extend and ulcerate if left untreated.
external image mole2.jpg
PIGMENTED BCC
This is similar to the nodular BCC but it has areas of pigmentation (darker areas). and could be confused with melanoma, a more serious cancer.
external image mole3.jpg
SUPERFICIAL BCC
The superficial BCC occurs mainly on the trunk as a red patch, usually up to 3cm in diameter. The edge of these tumours can be difficult to distinguish.
external image mole4.jpg
MORPHOEIC BCC
This looks like a firm yellow-white scar-like area and is often mistaken for one. These BCCs are often bigger than they first appear to the naked eye and may require special treatment techniques (see Mohs' Surgery).
Table 1.0 - Types of BCCs (Australian College of Dermatologists 2004)



Etiology and Epidemiology



The basal cell carcinoma tumour spreads by local extension. Basal cell carcinoma is a malignant tumour but metastatic spread is rare (less than 0.1%) even in advanced cases. Basal cell carcinoma typically occurs as a very slow growing lesion that can, in very advanced cases, become ulcerated and infiltrate surrounding structures such as bone or facial sinuses.

Probable Outcomes

Basal cell carcinoma is associated with an excellent prognosis. Even with late stage diagnosis cure is almost invariable with appropriate intervention. Although mortality for basal cell carcinoma is exceedingly low, advanced lesions can be associated with significant morbidity - in terms of disfigurement through local invasion and wound care difficulties in lesions that are extensively ulcerated. In the very few cases of metastatic basal cell carcinoma that have been described, death usually occurs within 8 months.


Diagnosis and Prognosis

A biopsy is required to diagnose skin cancer. A dermatologist can perform this simple procedure in the office by numbing the area and then removing the suspicious lesion (or a portion of it). The removed tissue is examined under a microscope to see if cancer is present. In some cases, the dermatologist might perform the biopsy and provide treatment during the same office visit.

Basal Cell Carcinoma
Basal Cell Carcinoma

Basal Cell Carcinoma

Basal Cell Carcinoma



Treatment


Optimal treatment for a given basal cell carcinoma depends upon both its size and location. Techniques can include cryosurgery, electrodessication and curettage, radiation therapy, topical 5-fluorouracil, surgical excision, or Mohs micrographic surgery - all of which are associated with very high rates of cure when selected appropriately by the treating specialist and individually suited to the basal cell carcinoma patients needs.

Most commonly, basal cell carcinoma treatment decisions are between radiotherapyand surgical excision, with surgical excision being the preferred treatment for almost all basal cell carcinomas.

For superficial BCC, topical 5-fluorouracil applied twice daily can be effective after 2-12 weeks and has a high cure rate. Its use in invasive tumours is not established. Iquimod 5% cream is effective in the treatment of superficial BCs and Bowen's disease, however its role in the treatment of other basal cell carcinoma is still under investigation.

The use of adjuvant systemic chemotherapy in BCC is in the research phase and is not currently part of routine management of BCC.

Improvement in basal cell carcinoma symptoms is an important measurement. Specific monitoring may be by clinical follow-up to detect recurrence or the appearance of new primary lesions. This should include visual inspection and palpation for any deeper recurrence, as well as questioning the patients about any altered sensation in the area of the lesion.

Almost 40% of patients with a single basal cell carcinoma will have a second primary within 5 years of the discovery of the initial tumour - so detailed and ongoing follow-up of all patients is very important.

The Basal cell carcinoma symptoms that may require attention are somatic pain from bony infiltration and neurogenic pain if nerve tissue is compressed. Wound care is important in basal cell carcinoma patients with advanced and ulcerative disease.


Regimens Used in the Treatment of This Disease:

Drugs/Products Used in the Treatment of This Disease:


TREATMENT

When the diagnosis is BCC, the dermatologist has a number of surgical and non-surgical options. The appropriate treatment depends on the size, location, and characteristics of the tumor, as well as the overall health and needs of the patient. Most BCCs are treated with one of the following:
  • SIMPLE SURGICAL EXCISION

The dermatologist cuts out the tumor and some of the surrounding healthy tissue. The removed tissue is examined under a microscope to see if all of the skin cancer has been removed.
  • MOHS MICROGRAPHIC SURGERY

Performed by a specially trained dermatologic surgeon, Mohs involves removing the visible tumor and then successive layers of skin one at a time until cancer cells are no longer found.
  • ELECTRODESICCATION AND CURETTAGE

The dermatologist removes the tumor by scraping or “curetting” it, and then burning the base with an electric needle. The latter is “electrodessication.”
  • CRYOSURGERY

The dermatologist destroys the tumor by freezing it with liquid nitrogen.
  • RADIATION THERAPY

High energy x–rays are used to damage/kill the cancer cells and prevent the growth of new cancer cells.
  • LASER SURGERY

High-intensity focused light waves are used to destroy the cancerous tissue.
  • TOPICAL THERAPY

The dermatologist prescribes a cancer-fighting medication, such as imiquimod or 5–fluorouracil, which the patient can apply to the skin cancer at home.
  • PHOTODYNAMIC THERAPY

A medication is applied to the skin, and light is used to activate the medication.


POST TREATMENT

After receiving treatment for BCC, follow-up appointments are scheduled. These appointments are essential because studies show that a person who develops BCC has an increased risk of developing another BCC or other form of skin cancer, including melanoma. Follow-up visits also are important because BCC can return after treatment. Cure rates and survival rates are highest with early detection and treatment.
You also should perform regular self–examinations of your skin as this can help detect skin cancer in its earliest stage. Be alert to any non-healing sore and other changes to your skin.


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Basal Cell Carcinoma
Basal Cell Carcinoma
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Basal Cell Carcinoma

Skin Mucosa and basal cells:


The skin is the largest organ of the body. It serves as a protective barrier between us and the environment, keeping water in and infection out. The skin in composed of two main layers:

  • The epidermis - consisting of keratinised stratified squamous epithelium; and
  • The dermis - a dense connective tissue.

Epidermal components of the skin include hair follicles and hair; sweat, sebaceous and mammary glands; and nails.

The functions of the skin include:
  • Providing a protective barrier from the external environment;
  • Homeostasis - assisting in the regulation of body temperature and water loss;
  • Sensory function - providing information about the external environment;
  • Excretion of body fluids - sweating; and
  • Synthesis of vitamin D on exposure to sunlight.

In addition, cells in the deep part of the epidermis make melanin to protect us from ultraviolet radiation. From a cancer viewpoint, the most important cells in the epidermis are squamous cells, basal cells and melanocytes.

Basal Cell Carcinoma of the Skin
Basal Cell Carcinoma of the Skin







Basal Cell Carcinoma


Copyrighted Material: Not for Reproduction or Distribution
Basal cell carcinoma (BCC) is the most common form of skin cancer. It also is the most common cancer in the world, and the number of cases continues to rise. The reason for this rise might be that people are receiving more unprotected exposure to the harmful ultraviolet (UV) rays of the sun. The likelihood of developing BCC also increases when you have one or more of the following risk factors

  • Fair skin.
  • Blond or red hair
  • Blue or green eyes
  • Family history of skin cancer
  • Weakened immune system
  • Received radiation therapy
  • Exposure to coal tar, pitch, creosote, or arsenic
Age is another risk factor. BCC can occur at any age, but the risk of developing this skin cancer increases significantly with age.

Basal cell cancer does not usually metastasize or travel in the bloodstream; rather it infiltrates the surrounding area and destroys the tissue. For this reason, basal cell cancer should be treated promptly by your dermatologist with dermatologic surgical techniques.



PREVENTION

Proper sun protection may prevent new skin cancers, even if you have had BCC. So that people know how to protect their skin from the sun, the American Academy of Dermatology created "Be Sun Smart".
  • Generously apply a broad-spectrum water-resistant sunscreen with a Sun Protection Factor (SPF) of 30 or more to all exposed skin. “Broad-spectrum” provides protection from both ultraviolet A (UVA) and ultraviolet B (UVB) rays. Reapply about every two hours, even on cloudy days, and after swimming or sweating.
  • Wear protective clothing, such as a long-sleeved shirt, pants, a wide-brimmed hat and sunglasses, where possible.
  • Seek shade when appropriate, remembering that the sun’s rays are strongest between 10 a.m. and 4 p.m. If your shadow is shorter than you are, seek shade.
  • Protect children from sun exposure by playing in the shade, using protective clothing, and applying sunscreen.
  • Use extra caution near water, snow, and sand because they reflect the damaging rays of the sun, which can increase your chance of sunburn.
  • Get vitamin D safely through a healthy diet that may include vitamin supplements. Don't seek the sun.
  • Avoid tanning beds. Ultraviolet light from the sun and tanning beds can cause skin cancer and wrinkling. If you want to look like you've been in the sun, consider using a sunless self-tanning product, but continue to use sunscreen with it.




References

Abeloff, M.D., Armitage, J.O., Niederhuber, J.E., Kastan, M.B. & McKenna, W.G. (2008), Abeloff's Clinical Oncology Fourth Edition, Elselvier Inc., Philadelphia, USA

American Academy of Dermatology (2009), Basal Cell Carcinoma, viewed 15th September 2009,
http://www.aad.org/public/publications/pamphlets/sun_basal.html

American Cancer Society, Inc (2009), ACS :: Detailed Guide: Skin Cancer - Basal and Squamous Cell, viewed 20th August 2009,
http://www.cancer.org/docroot/CRI/CRI_2_3x.asp?dt=51

Australian Government Department of Health and Ageing (2008), Skin Cancer - Basal Cell Carcinoma (BCC), viewed 20th September 2009,
http://www.skincancer.gov.au/internet/skincancer/publishing.nsf/Content/fact-bcc

Bath-Balogh, M. & Fehrenbach, M.J. (2006), Illustrated Dental Embryology, Histology and Anatomy Second Edition, Elsevier Inc., Missouri, USA

Ibsen, O.A.C., & Phelan, J.A., Oral Pathologist for the Dental Hygienist Fourth Edition, Elsevier Inc., Missouri, USA

Illumistream (2007), "Understanding Basal Cell Carcinoma (Skin Cancer #4)", © YouTube, LLC, http://www.youtube.com/watch?v=Yy6yHa_HtXI

Marieb E.N & Hoehn K (2005), Human Anatomy & Physiology Seventh Edition, Pearson Benjamin Cummings, San Francisco, USA

Regezi, J.A., Sciubba, J.J. & Jordan, R.R. (2002), Oral Pathology - Clinical Pathological Correlations Fourth Edition, Elsevier Inc., Philadelphia, USA

Sullivan, J.R. (2004), A-Z of Skin: Types of Skin Cancers, Australian College of Dermatologists, viewed 15th September 2009,
http://www.dermcoll.asn.au/public/a-z_of_skin-types_of_skin_cancers.asp

Washingtondeceit (2008), "How To Identify Skin, Lip-Basal Cell Carcinoma", © Howcast Media, Inc, http://www.howcast.com/videos/19536-How-To-Identify-Skin-LipBasal-Cell-Carcinoma