Basal cell carcinoma
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Basal Cell Carcinoma
Definition
BCC is a nonmelanocytic skin cancer usually confined to hair bearing skin.
Epidemiology
This cancer is quite common in Caucasian people over the age of 40. Males are more affected than females. It is 4 times more common than Squamous cell cancer. Etiology Sun exposure and damage is the major cause of this cancer. Primarily, the insult is due to UVR particularly UVB radiation occurring at a wavelength of 290- 230 nm. UVB incites DNA mutations and produces Thymidine dimers in the TSG p53. Other people are unfortunately genetically predisposed to acquiring skin cancers. Examples include Xeroderma pigmentosum, Gorlin’s basal cell nevus syndrome and familial melanoma syndromes. Patients with XP are unable to repair the UV induced damage and are tend to develop both BCC and SCC under the age of 10 years. With Gorlin’s, patients develop BCC in their teens and brain tumors. This mutation is in a Patched (PTCH) gene playing part in the Hedgehog signal transduction pathway. Radiation is also an inciting factor.
Predisposing factors
Skin phototypes I, II and albinos are more susceptible to getting BCC through prolonged sun exposure. Ingestion of arsenic leads increases risk to getting superficial multicentric BCC 30-40 years later. Previous therapy with X-rays for acne also potentiates the risk in all skin phototypes.
Clinical Manifestation
BCC arises in the basal cell layer of the skin. It is mostly seen on chronically sun exposed areas of the skin like face, head (scalp included), neck, and hands. It rarely metastasizes and is slow growing. It is however locally invasive and is usually fatal in this manner. There are 5 clinical types:
Nodular BCC Cystic, portions of nodular BCC may have areas of melanin pigmentation, keratotic; the most common type of BCC; usually presents as a round, translucent (‘’pearly’’), well defines and firm flesh-colored or red papule or nodule with telangiectases.
Ulcerating BCC Rodent ulcer with rolled up edges, translucent, pearly, smooth, firm with telangiectasia.
Sclerosing BCC Appears as a small patch of morphea or a superficial scar, often ill defined, skin-colored, whitish but also with peppery pigmentation In this infiltrating type of BCC there is an excessive amount of fibrous stroma. Histologically, finger-like strands of tumor extend far in to the surrounding tissue, and excision therefore requires wide margins. Sclerosing BCC can progress to nodular or ulcerating BCC.
Superficial multicentric BCCs Appear as thin plaques of Pink or red; characteristic fine threadlike border and telangiectasia can be seen with the aid of a hand lens. This is the only form of BCC that can exhibit a considerable amount of scaling. This can also give rise to nodular and ulcerating BCC. BCC often bleeds with minimal excoriation by fingernail.
Pigmented BCC Lesion may be brown to blue or black Smooth, glistening surface; hard, firm; may be indistinguishable from superficial spreading or nodular melanoma but is usually harder. Cystic lesions may occur: round, oval shape, depressed center (“umbilicated”). Stippled pigmentation can be seen in any of BCC types.
Treatment
Goal is to treat local disease and also to attain the best cosmesis for the patient. A complete skin exam is warranted due to the hightened risk of actinic keratosis or cancers arising at other skin sites in persons coming in with a suspicious lesion. Excision with primary closure, skin flaps, or grafts. Curetagge is good for small, nodular lesions less than 1cm and thus offers good cosmesis. Cryotherapy itself is for lesions less than 2cm but in this case may leave an area of depigmentation. For lesions in the danger sites (nasolabialarea, around the eyes, in the ear canal, in the posterior auricular sulcus, and on the scalp)and sclerosing BCC, microscopically controlled surgery (Mohs surgery) is the best approach. Radiation therapy is an alternative only when disfigurement may be a problem with surgical excision (e.g., eyelids or large lesions in the nasolabial area) or in very old age. It also has the advantage of no pain, no hospitalization and no keloids or contractures. It does however produce some depigmentation, loss of hair follicles and sweat glands at the treated site. Topical 5-fluorouracil 5% cream may be used to treat small, superficial BCCs in low-risk areas. It interferes with DNA synthesis by blocking methylation of deoxyuridylic acid and inhibiting thymidylate synthetase and, subsequently, cell proliferation. Side effects include progressive inflammation, erythema erosions and contact dermatitis. Interferon alfa-2b is a protein product manufactured using recombinant DNA technology. It has shown some success in treating small (< 1 cm), nodular, and superficial BCCs. The receptor-selective acetylenic retinoid tazarotene (Tazorac) can also be used to treat small low-risk BCCs. Tazarotene is thought to cause BCC regression by increasing apoptosis and by decreasing cell proliferation in the skin cancer cells. Imiquimod 5% cream (Aldara) is approved by the US Food and Drug Administration for the treatment of nonfacial superficial BCC. Systemic chemotherapy is only for treating locally advanced and metastatic disease. Most used regimen is Cisplatin in combination with 5-fluorouracil or doxorubicin.
Prevention
References
http://caci.co.nz/skin-phototype-fitzpatrick
Mark Bower, Jonathan Waxman, Lecture Notes Oncology, Blackwell Publishing, 2006
Klaus Wolff, Richard Allen Johnson, Fitzpatrick’s Colour Atlas and Synopsis of Clinical Dermatology, 6th Ed, McGraw-Hill, 2009
http://emedicine.medscape.com/article/276624-overview
http://www.healthcentral.com/skin-cancer/000431.html
