Signs, Symptoms, and Diagnosis of Basal-cell Carcinoma - Shiny, pearly skin nodule - Red patch similar to eczema - Skin thickening or scar tissue - Difficulty in visually distinguishing from other skin conditions - Diagnosis requires tactile sensation and skin biopsy - Skin biopsy is performed for histopathologic analysis - Shave biopsy under local anaesthesia is the most common method - Clinical diagnosis is possible for most nodular basal-cell cancers - Exfoliative cytology methods can confirm the diagnosis when clinical suspicion is high - Differential diagnosis can be challenging with other benign lesions

Causes and Pathophysiology of Basal-cell Carcinoma - Majority of basal-cell carcinomas occur on sun-exposed areas - Risk factors include exposure to ultraviolet light, lighter skin, radiation therapy, long-term exposure to arsenic, and poor immune-system function - UV light exposure during childhood is particularly harmful - Tanning beds are a common source of ultraviolet radiation - Unclear whether sunscreen affects the risk of basal-cell cancer - Basal-cell carcinoma originates from basal cells in the lowest layer of the epidermis - Trichoblasts are the cells thought to develop into basal-cell carcinoma - Overexposure to sunlight leads to DNA damage and mutations - Local immune system depression due to sun exposure may decrease immune surveillance - Basal-cell carcinoma can be associated with other skin lesions

Types and Subtypes of Basal-cell Carcinoma - Superficial basal-cell carcinoma characterised by superficial proliferation of neoplastic basal cells - Infiltrative basal-cell carcinoma penetrates into deeper layers of the skin - Nodular basal-cell carcinoma is the most common type and shows heterogeneous morphologic features - Cystic basal-cell carcinoma - Dome-shaped, blue-gray cystic nodules - Morpheaform basal-cell carcinoma - Narrow strands and nests of basaloid cells, surrounded by dense sclerotic stroma - Aggressive subtype - Micronodular basal-cell carcinoma - Small and closely spaced nests - Superficial basal-cell carcinoma - Appears as an erythematous patch on the trunk - Aggressiveness patterns: low-level aggressive pattern, moderately aggressive pattern, highly aggressive pattern, cohesive nodular pattern, superficial pattern, fibroepitheliomatous pattern

Treatment Options for Basal-cell Carcinoma - Cryosurgery: Good cure rate when accurately utilised, disadvantages include lack of margin control, tissue necrosis, over or under treatment of the tumor, and long recovery time - Electrodesiccation and curettage: Scrape away the soft cancer using a round knife, followed by burning the skin with an electric current, generally used on cosmetically unimportant areas - Chemotherapy: Some superficial cancers respond to local therapy with 5-fluorouracil, chemotherapy often follows Mohs surgery, experimental procedures involving curettage followed by chemotherapy are not standard care - Immunotherapy: Uses the body's immune system to kill cancer cells, topical treatment with 5% imiquimod cream has a reported success rate, off-label use of imiquimod on invasive basal-cell carcinoma has been reported - Radiation: Delivered as external beam radiotherapy or brachytherapy, generally used in older patients or cases where surgical excision will be disfiguring or difficult to reconstruct, cure rate varies depending on tumor size - Photodynamic therapy: Administered by applying photosensitizers and activating them with light, good treatment option for primary superficial BCCs and reasonable for low-risk nodular BCCs, poor option for high-risk lesions - Mohs surgery: Effective for primary and recurrent forms of BCC, examines the entire surgical margin for cancer cells, higher cure rates compared to other treatments

Prognosis, Prevention, and Epidemiology of Basal-cell Carcinoma - Prognosis is excellent if the appropriate method of treatment is used in early primary basal-cell cancers - Recurrent cancers are harder to cure with a higher recurrence rate - Basal-cell carcinoma rarely metastasizes but grows locally with invasion and destruction of local tissues - The vast majority of cases can be successfully treated before serious complications occur - The recurrence rate for treatment options ranges from 50 percent to 1 percent or less - Basal-cell cancer is a very common skin cancer, more common in fair-skinned individuals with a family history, incidence increases closer to the equator or at higher altitude, very common among elderly people over the age of 80, approximately 800,000 new cases occur yearly in the United States