Basal cell carcinoma (BCC) is a malignant skin tumor that grows slowly and very rarely metastasizes, but it is locally invasive and destructive. It belongs to the group of non-melanocytic skin cancers. It arises from undifferentiated cells of the basal layer of the epidermis and skin appendages. BCC is the most common malignant skin tumor in the white population, accounting for 75% of all skin cancers.
Basal cell carcinoma may initially present as:
- A pink papule that gradually enlarges
- An erosion that shows no tendency to heal
- A pearly-colored nodule with a smooth, shiny surface and the characteristic presence of fine telangiectasias
The typical clinical appearance of basal cell carcinoma usually becomes clearer after a considerable period from its onset. Patients often mistake it for another skin condition, such as xerosis or eczema, before consulting a dermatologist.
Basal cell carcinomas typically appear (in 80% of cases) on the face and neck—especially on the eyelids, zygomatic area, cheeks, forehead, upper lip, and nose—and less frequently in other areas of the body. In most cases, they develop in sun-exposed areas and usually appear as solitary lesions. The occurrence of two or more basal cell carcinomas in the same individual is much rarer.
The differential diagnosis is broad and includes both benign and malignant skin conditions and tumors. On one hand, basal cell carcinoma may mimic benign conditions such as intradermal nevi, sebaceous hyperplasia, molluscum contagiosum, psoriasis, and eczema, potentially delaying diagnosis. On the other hand, it may clinically resemble malignant tumors such as squamous cell carcinoma, keratoacanthoma, Bowen’s disease, or even melanoma.
According to Lever, there is a wide variety of clinical types of BCC. More specifically, it is classified into:
- Nodular–ulcerative (the most common type)
- Pigmented
- Sclerodermiform (morpheaform)
- Superficial or pagetoid
- Fibroepithelioma of Pinkus
- Multiple basal cell carcinoma syndrome
- Linear and generalized follicular basal cell nevus
- Basex-Rombo syndrome
- BCC arising on sebaceous nevus of Jadassohn
- Basosquamous carcinoma (metatypical carcinoma).
The incidence of basal cell carcinoma (BCC) in the United States is approximately 900,000 cases per year. It occurs more frequently in men than in women, although a rising trend in female cases has been observed in recent years.
The annual incidence rate of BCC is 146 per 100,000 inhabitants in the U.S., 132 per 100,000 in Europe, and between 1,000–2,000 per 100,000 in Australia. Although no official global statistics are available, a yearly increase in incidence of around 10% is estimated worldwide.
In Greece, there are no official data; however, an increasing number of cases are being recorded in patients presenting to dermatology clinics. Basal cell carcinoma is extremely rare among individuals of Black ethnicity.
It typically appears after the age of 40, with incidence increasing with age. About 80% of cases occur in patients over 60 years old. Nevertheless, it can develop at any age, even in children (e.g., in Gorlin syndrome or in immunosuppressed individuals). Notably, the highest rate of increase in BCC cases is observed in the 30–49 age group.
- Ultraviolet (UV) radiation
Prolonged and long-term sun exposure during childhood and adolescence, especially when associated with frequent sunburns, is considered the most important risk factor. - Individual phenotypic characteristics
Fair skin, blond or red hair, freckles, combined with sunburns in childhood, are associated with an increased risk of developing BCC. - Radiodermatitis
Caused by therapeutic use of Roentgen rays. - Heredity
Conditions such as the basal cell nevus syndrome (Gorlin syndrome), xeroderma pigmentosum, and other rare genetic syndromes. - Post-burn scars, chronic non-healing ulcers, sebaceous nevi, and adnexal hamartomas.
- Chronic occupational or recreational outdoor activities.
- Occupational exposure to arsenic.
- History of photochemotherapy (PUVA), phototherapy (UVB), or radiotherapy.
- Immunosuppression
Due to medications, non-Hodgkin lymphoma, or HIV infection. - Personal history of basal cell carcinoma It is estimated that 40–50% of patients with BCC will develop a new neoplasm within the next five years.
The treatment options for BCC are individualized based on the clinical presentation and the patient’s medical history, and include the following:
- Surgical excision with histopathological examination
- Microscopically controlled surgery (MOHS)
- Electrocautery, dermabrasion, and CO₂ laser treatment
- Cryosurgery
- Radiotherapy
- Photodynamic therapy
- Retinoids
- Topical chemotherapeutic agents (podophyllin, 5-fluorouracil, imiquimod)
- Interferon (intralesional injections)
- Vismodegib – an orally available small-molecule inhibitor of the Hedgehog signaling pathway.
The prognosis is excellent when BCC is diagnosed and treated promptly, appropriately, and thoroughly. It rarely metastasizes. According to studies, the likelihood of metastasis ranges from 0.0028% to 0.1%. Metastasis primarily occurs in extensive, ulcerated, and especially neglected BCCs. The most common sites of metastasis include regional lymph nodes, lungs, bones, and others.
It is a rare syndrome inherited in an autosomal dominant manner, with an estimated frequency of 1 in 56,000 individuals. It is characterized by the development of basal cell carcinomas beginning in childhood, and even infancy, which continue to appear throughout life.
Lesions primarily occur in sun-exposed areas, with characteristic involvement of the palms. Associated manifestations include palmar pits, odontogenic cysts of the lower jaw, hypertelorism, and other tumors (such as ovarian fibromas and medulloblastoma).
Here comes the good news: BCC very rarely causes metastases and primarily has a locally destructive effect on the skin and underlying tissues. Furthermore, early diagnosis and treatment lead to cure without resulting in disfigurement or aesthetic alterations caused by extensive surgical procedures.
There are certain specific subtypes of BCC (such as superficial BCC) that may be treated with local destructive methods (e.g., cryotherapy). However, surgical excision of BCC has a significantly lower recurrence rate compared to these methods.
BCCs have a tendency to recur, especially those located on the head and nose. For this reason, regular and systematic follow-up is recommended after treatment—not just in the short term.