Today we will be discussing basal cell carcinoma.These are non-melanotic cancerous growths of the skin, that arise from the basal cells, in the lower dermis.Basal cell carcinomas require stroma surrounding them for support. Therefore, it makes them very difficult to metastasize by blood or lymphatic system.
There are multiple classifications of basal cell carcinomas including nodular, cystic, pigmented, superficial, sclerosing or morpheaform, and nevoid.
The most common of the six classifications is nodular, occurring in around 21 percent of cases.The least common is morpheaform, occurring in approximately 1 percent of cases.Mixed histologic patterns are seen roughly 40 percent of the time.
Basal cell carcinoma is the most common dermatologic neoplasm, with 85 percent of cases being seen in the head and neck areas.The most common site is the nose at 30 percent of cases.
Basal Cell Carcinoma Risk Factors
There is an increased prevalence with age, with an increased incidence in patient’s over 40 years of age.In addition, men are more likely to be affected by basal cell carcinomas as compared to women.
Other risk factors include having fair skin, use of tanning beds (specifically UV-A and UV-B radiation), increased sun exposure, history of radiation therapy, impaired immune system, and personal or family medical history of skin cancers.
Regarding screening, the USPSTF has not found sufficient data to support routine screening for skin cancer using whole-body skin examinations.Although, they recommend that providers remain alert for skin lesions with potential malignant features.
I tend to ask on a yearly basis if a patient has any new or changing skin spots that they are worried about that they would like for me to take a look at.A mentor once told me, “you aren’t going to find abnormal skin spots unless you ask about them!”
The American Cancer Society recommends a “cancer-related checkup” including a skin examination every three years in those age 20 to 40 years, and a yearly exam in those over 40 years of age.They also recommend a monthly self-skin examination.
The histologic type of basal cell carcinoma will often dictate how it will present clinically.Most commonly, nodular types will have the classic dome-shaped, painless lesion, that frequently has an ulceration with rolled borders.Additionally, they can have surrounding telangiectatic vessels, with the boundaries being pearly.
Superficial basal cell carcinomas are well circumscribed with scaling, a black appearance, and a thin raised pearly white border.Crusting and erosions may be present as well.These types of BCCs most commonly occur on the trunk and extremities.These can often resemble eczema or psoriasis.
Morpheaform lesions are often flat or slightly raised lesions that are yellow or white with appearances similar to a scar.The surface will usually have a waxy consistency.These do not have the classic pearly white bordered appearance.
BCC can also be pigmented in which histologically they contain melanin.This will give the lesion a bluish, black, or brown color.These are often misdiagnosed as melanoma.
Diagnosing Basal Cell Carcinoma
Diagnosis of basal cell carcinoma relies upon tissue sampling via biopsy.This can be done by shave biopsy or by using a 2 to 4 mm punch biopsy on the most abnormal area of skin.Complete excision may be required as the initial diagnostic procedure for small lesions.
Pigmented lesions, or those that have any concerning features of melanoma. should be evaluated by using a full-thickness technique.When in doubt, regarding performing a biopsy of an area concerning for melanoma, refer to dermatology.
Treatment of basal cell carcinoma varies based on the lesion size, cell type, and location.Full excision typically done via surgery is recommended for large basal cell carcinomas with defined borders, specifically on the trunk, forehead, facial cheeks, and legs.
Mohs’ micrographic surgery is preferred in areas of high risk such as the nose and eyelids.Additionally, Mohs’ technique is used in extensive primary tumors, recurrent BCCs, and lesions with poorly defined borders.
Electrodissection and curettage are applied on lesions that are small and nodular in type.
Liquid nitrogen cryosurgery is useful in basal cell carcinomas that are nodular or superficial with clear margins.This method is typically saved for uncomplicated lesions.Before performing cryotherapy as a treatment for BCCs, biopsy MUST be completed to determine the depth of the lesion.
For those that are more than 3 mm deep, cryotherapy as treatment is not indicated.
Radiation therapy is used for basal cell carcinomas that are in locations that require preservation of the surrounding tissue for cosmetic appearance, such as around the lips.It is also useful in patients that cannot tolerate a surgical procedure for large lesions.
Imiquimod or fluorouracil can be used for small superficial basal cell carcinomas on the trunk or extremities.The most prominent advantage of this therapy is that there is a lack of scarring compared to more invasive techniques.
A review in 2009 found that Imiquimod had a wide range of clearance rates.This was dependent upon the drug regimen and the tumor’s histological type.Data supports the use of this medication as monotherapy for superficial BCCs, but the strength of this recommendation is weak.
Overall, the use of this medication should only be applied to small, superficial basal cell carcinomas in low-risk locations in patients who are unwilling or unable to undergo other more effective or better-established therapies.
Vismodegib is an oral medication that is a hedgehog pathway inhibitor that can be used for metastatic basal cell carcinomas, recurrent basal cell carcinomas, and locally advanced basal cell carcinoma in patients who are non-surgical candidates.The dosing of this medication is 150 mg daily, and the cost is around $7,000 for a one month supply.
Basal Cell Carcinoma Recurrence
Unfortunately, there is a variability in the reporting of the recurrence rates of basal cell carcinomas of each treatment method.
The risk of recurrence of a BCC is dependent upon many factors including location of lesion, size of the lesion, and the histologic subtype.Other contributors include age, sex, and immune status of the patient.
Mohs’ surgery has the lowest recurrence rate.Unfortunately, due to cost and reduced availability, it is best to use this for large lesions (greater than 2 cm in size), tumors with aggressive histologic subtype, and on sites of high recurrence.
The recurrence rate after Mohs’ surgery is around 1 percent at five years.
Lesions not in the “H-zone” of the face can be treated with general surgical excision.The recurrence rate of this method is around 5 percent at five years.
Incomplete resection of the primary lesion after a general excision attempt, seen by pathology showing tumor at the surgical margin, should be followed with re-excision or Mohs’ surgery to assure complete resection.
Recurrence rate after removal via electrodissection depends on the individual risk of recurrence of the location of the lesion.In low-risk areas, the rate of recurrence is 8.6 percent.
In intermediate-risk locations, the recurrence rate is 12.9 percent, and in high-risk areas, the rate of recurrence is 17.5 percent.
For cryotherapy, 5-year recurrence rate is 3.5 to 16.5 percent based on the size and location of the skin lesion
Am Fam Physician. Diagnosis and Treatment of Basal Cell and Squamous Cell Carcinoma. 2012 Jul 15;86(2):161-168.
UpToDate. Epidemiology, pathogenesis, and clinical features of basal cell carcinoma. Accessed: December 13, 2017.
UpToDate. Treatment and prognosis of basal cell carcinoma at low risk of recurrence. Accessed: December 13, 2017.
Ferri’s Clinical Advisor, 2017.
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