Basal cell carcinoma overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Maneesha Nandimandalam, M.B.B.S.[2] Saarah T. Alkhairy, M.D.,
Overview
The classification of basal cell carcinoma (BCC) is divided into many clinical variants. There are many causes associated with basal cell carcinoma such as sunlight, gene mutations, and other conditions, for example, xeroderma pigmentosum. There are several differential diagnosis for basal cell carcinoma that may be differentiated clinically or histopathologically including microcystic adnexal carcinoma, trichoepithelioma/trichoblastoma, merkel cell carcinoma, and other squamous cell carcinoma. In 2014, the average annual incidence of basal cell carcinoma in the United States was 878 cases per 100,000 individuals. The U.S. Preventive Services Task Force has found no evidence to recommend for or against screening. The American Cancer Society recommends that a health care provider examine the skin every year if the patient is older than 40 years, and every 3 years if the patient is between 20-40 years. Basal cell carcinoma is slow-growing and locally invasive. Common complications of BCC include reoccurrence and development of other types of skin cancer. The American Joint Committee on Cancer (AJCC) stages basal cell carcinoma based on the TNM system. T, M, and N are combined into stages, called stage grouping. The history and symptoms of basal cell carcinoma include skin growths on sun-exposed skin. The physical examination of basal cell carcinoma is based on a clinical exam. The laboratory tests of basal cell carcinoma consist of a biopsy and visualization of its histological findings. After the suspicious lesion is evaluated, the medical therapy is divided into low-risk and high-risk basal cell carcinoma patients. Medical therapy consists of surgery, radiation therapy, and follow-up for recurrence. Types of surgery for basal cell carcinoma involve electrodesiccation and curettage, surgical excision, mohs micrographic surgery, and cryosurgery. The primary prevention of basal cell carcinoma involves avoidance and protection from the sun. A skin biopsy and chemotherapeutic agents such as 5-Fluorouracil or Imiquimod may prevent the further development of basal cell carcinoma.
Historical Perspective
In 1827, Jacob Arthur, reported the "rodent ulcer". In 1900, Edmund Krompecher, identified the histological features as an epithelial carcinoma.
Classification
There is no well established classification for basal cell carcinoma, however there are few clinical variants which are nodular, cystic, sclerodermiform, infiltrated, micronodular, superficial, and pigment basal cell carcinoma and fibroepithelioma of Pinkus.
Pathophysiology
Basal cell carcinoma is one of the most common skin cancers. It is commonly known as rodent ulcer due to its distinct morphology characterized by pearly pink nodules with telangiectasias, rolled borders, and central crusting with or without an ulcerating lesion. The most common cause for the development of the basal cell carcinoma involves radiation exposure and mutations that involve many genes including sonic hedgehog gene, PTCH1 gene, and other gain-of-function mutations which further depend on the subtypes such as nodular, superficial, Infundibulocystic, fibroepithelial, morpheaform, infiltrative, micronodular, and basosquamous basal cell carcinomas.
Causes
Although the exact causes were unknown, the following are some of the factors that have been associated with the development of basal cell carcinoma: radiation exposure, gene mutations, xeroderma pigmentosa, epidermodysplastic verruciformis, nevoid basal cell carcinoma syndrome, bazex syndrome, rombo syndrome etc.
Differential Diagnosis
There are several differential diagnosis for basal cell carcinoma that may be differentiated clinically or histopathologically including microcystic adnexal carcinoma, trichoepithelioma/trichoblastoma, merkel cell carcinoma, and other squamous cell carcinoma.
Epidemiology and Demographics
The annual incidence of basal cell carcinoma in the United States is approximately 2.8 million which increases with increasing age. Men and white skinned people are affected relatively more, especially in states closer to the equator.
Risk Factors
Environmental and genetic risk factors that may predispose to basal cell carcinoma include radiation exposure, physical characteristics, gender, albinism, xeroderma pigmentosum, epidermodysplastic verruciformis, nevoid basal cell carcinoma syndrome, bazex syndrome, rombo syndrome etc.
Screening
The U.S. Preventive Services Task Force has found no evidence to recommend for or against screening. The American Cancer Society recommends that a health care provider examine the skin every year if the patient is older than 40 years, and every 3 years if the patient is between 20-40 years.
Natural History, Complications, and Prognosis
Basal cell carcinoma is slow-growing and locally invasive. Common complications of BCC include reoccurrence and development of other types of skin cancer.
Staging
The American Joint Committee on Cancer (AJCC) stages basal cell carcinoma based on the TNM system. T, M, and N are combined into stages, called stage grouping.
History and Symptoms
The history and symptoms of basal cell carcinoma include skin growths on sun-exposed skin. They are fragile and may bleed easily.
Physical Examination
The physical examination of basal cell carcinoma is based on a clinical exam.
Diagnostic Studies
Laboratory Findings
The laboratory tests of basal cell carcinoma consist of a biopsy and visualization of its histological findings.
Other Diagnostic Studies
CT scans and radiography may be performed if there is involvement of deeper structures, such as the bone.
Medical Therapy
After the suspicious lesion is evaluated, the medical therapy is divided into low-risk and high-risk basal cell carcinoma patients. Medical therapy consists of surgery, radiation therapy, and follow-up for recurrence.
Surgery
Types of surgery for basal cell carcinoma involve electrodesiccation and curettage, surgical excision, mohs micrographic surgery, and cryosurgery.
Primary Prevention
The primary prevention of basal cell carcinoma involves avoidance and protection from the sun.
Secondary Prevention
A skin biopsy and chemotherapeutic agents such as 5-Fluorouracil or Imiquimod may prevent the further development of basal cell carcinoma.
References