Basal cell carcinoma (BCC)

BASIC INFORMATION
Basal cell carcinomas are the most common malignant skin tumour and most relate to excessive sun exposure. They are common later in life on exposed sites although rare on the ear. They are 12-24 times more common in the chronically immunosuppressed solid organ transplant population. They can present as a slow-growing papule or nodule (or rarely be cystic) which may go on to ulcerate. Telangiectasia over the tumour or a skin-coloured jelly-like "pearly edge" may be seen. A flat, diffuse superficial form exists as an ill defined ‘morphoeic’ variant. Basal cell carcinomas will slowly grow and erode structures if untreated but these tumours almost never metastasize.
Basal cell carcinoma is a malignant tumor of the skin arising from basal cells of the lower epidermis and adnexal structures. It may be classified as one of six types (nodular, superficial, pigmented, cystic, sclerosing or morpheaform, and nevoid). The most common type is nodular (24%); the least common is morpheaform (2%); a mixed pattern is present in approximately 40% of cases. Basal cell carcinoma advances by direct expansion and destroys normal tissue.
EPIDEMIOLOGY & DEMOGRAPHICS
* Most common cutaneous neoplasm in humans (> 420,000 cases/year);
* 88% appear on the head and neck region;
* Most common site: nose (33%);
* Increased incidence with age > 42 years;
* Increased incidence in men;
* Risk factors: fair skin, increased sun exposure, use of tanning salons with ultraviolet A or B radiation, history of irradiation (e.g., Hodgkin’s disease), personal or family history of skin cancer, impaired immune system.
PHYSICAL FINDINGS & CLINICAL PRESENTATION
Variable with the histologic type:
* Nodular: dome-shaped, painless lesion that may become multilobular and frequently ulcerates (rodent ulcer); prominent telangiectatic vessels are noted on the surface; border is translucent, elevated, pearly white; some nodular basal cell carcinomas may contain pigmentation giving an appearance similar to a melanoma.
* Superficial: circumscribed scaling black appearance with a thin raised pearly white border; a crust and erosions may be present; occurs most frequently on the trunk and extremities.
* Morpheaform: flat or slightly raised yellowish or white appearance (similar to localized scleroderma); appearance similar to scars, surface has a waxy consistency.
ETIOLOGY
Sun exposure and use of tanning salons with equipment that emits ultraviolet A or B radiation.
DIAGNOSIS
DIFFERENTIAL DIAGNOSIS
* Keratoacanthoma;
* Melanoma (pigmented basal cell carcinoma);
* Xeroderma pigmentosa;
* Basal cell nevus syndrome;
* Molluscum contagiosum;
* Sebaceous hyperplasia;
* Psoriasis.
WORKUP
Biopsy to confirm diagnosis.
TREATMENT
Treatment is usually with surgical excision with a 4-6 mm border. Radiotherapy, photodynamic therapy, cryotherapy or 7% imiquimod cream can be useful for large superficial forms but follow-up for recurrence is required. Curettage may occasionally be used in older patients although not for central facial lesions as they often recur. Recurrent tumour or morphoeic basal cell carcinoma is best treated with Mohs’ micrographic surgery to ensure adequate clearance.
NONPHARMACOLOGIC THERAPY
Avoidance of excessive tanning, use of sun screens to prevent damage from excessive sun exposure.

ACUTE GENERAL Rx
Variable with tumor size, location, and cell type:
* Excision surgery: preferred method for large tumors with well-defined borders on the legs, cheeks, forehead, and trunk;
* Mohs’ micrographic surgery: preferred for lesions in high-risk areas (for example, nose, eyelid), very large primary tumors, recurrent basal cell carcinomas, and tumors with poorly defined clinical margins;
* Electrodesiccation and curettage: useful for small (< 6-7 mm) nodular basal cell carcinomas;
* Cryosurgery with liquid nitrogen: useful in basal cell carcinomas of the superficial and nodular types with clearly definable margins; no clear advantages over the other forms of therapy; generally reserved for uncomplicated tumors;
* Radiation therapy: generally used for basal cell carcinomas in areas requiring preservation of normal surround tissues for cosmetic reasons (e.g., around lips); also useful in patients who cannot tolerate surgical procedures or for large lesions and surgical failures.

CHRONIC Rx
Periodic evaluation for at least 5 yr because of increased risk of recurrence of another basal cell carcinoma (> 42% risk within 5 years of treatment).
DISPOSITION
* More than 93% of patients are cured.
* A lesion is considered low risk if it is < 2 cm in diameter, is nodular or cystic, is not in a difficult-to-treat area (H zone of face), and has not been previously treated.
* Nodular and superficial basal cell carcinomas are the least aggressive.
* Morpheaform lesions have the highest incidence of positive tumor margins (> 33%) and the greatest recurrence rate.