Squamous cell carcinoma : SCC

Skin cancer ---> Non melanoma skin cancer ---> squamous cell carcinoma

Squamous cell carcinoma is a malignant invasive proliferation of epidermal keratinocytes.
Epidemiology
Squamous cell carcinoma is the second most common type of skin cancer. It is more common in men and in the elderly population.
Pathology
There is a relationship with chronic ultraviolet exposure. Squamous cell carcinoma is especially common in individuals with skin phototypes I and II. Other etiological factors include topical and systemic carcinogens such as arsenic, photochemotherapy (PUVA) and chronic immunosuppression (following allogeneic organ transplantation or in those with lymphoma or leukemia). The lesions may also arise at sites of long-standing radiation dermatitis, scarring (discoid lupus erythematosus), ulceration and pre-existing lesions such as Bowen's disease. Some squamous cell carcinomas are associated with human papillomavirus infection. Smoking is associated with lesions on the lip.
Scope of disease
Squamous cell carcinoma is locally invasive and has the potential to metastasize to lymph nodes and other organs of the body.
Clinical features
Squamous cell carcinoma usually presents as an expanding plaque or nodule with an ill-defined, indurated base and surface crusting. The lesion may ulcerate. It is most often seen on sun-exposed sites (face, neck, forearms and dorsum of hands) in association with solar elastosis and multiple actinic keratoses. Local lymph nodes may be enlarged with metastatic involvement.
Investigations
Skin biopsy
A skin biopsy is required to establish a histopathological diagnosis and to gain information on the degree of differentiation, grade, depth and level of dermal invasion, the presence of perineural, vascular or lymphatic invasion, and clearance margins of the excised tissue.
Lymph node biopsies
Squamous cell carcinomas usually spread to local lymph nodes; therefore clinically enlarged nodes should be excised and submitted for histopathological analysis.
Initial management
Patient education
Sun avoidance, the use of sunscreen and protective clothing are the main steps in the prevention of actinic keratosis and further squamous cell carcinomas, particularly in patients receiving immunosuppression.
Multidisciplinary team approach
There is overlap between dermatologists, clinical oncologists and plastic surgeons in the management of patients with squamous cell carcinoma, and therefore a multidisciplinary approach is favored.
Surgical management
Curettage and cautery
Curettage and cautery may be feasible treatment options for small, well-defined, low-risk tumors.
Excision biopsy and regional node dissection
Surgical excision or Mohs' micrographic surgery is the treatment of choice for the majority of lesions. For low-risk tumors (less than 2 cm in diameter), excision with a 4 mm margin is expected to achieve complete cure in 95%.
Mohs' micrographic surgery is indicated for larger, higher-risk tumors. With this technique, each section is examined with frozen section analysis to determine the completeness of resection. It is particularly useful in difficult sites where wide surgical margins may be technically difficult to achieve without functional impairment.
Tumor-positive lymph nodes are usually managed by regional node dissection.
Medical management
Radiotherapy
Other treatment options include radiotherapy for non-resectable tumors or lymph node disease.
Prognosis
Squamous cell carcinoma has an overall remission rate after therapy of 90%. The factors that influence metastatic potential include anatomical site, tumor size, degree of differentiation and immunosuppression. Tumors arising in areas of radiation injury, chronic inflammation or chronic ulcers have the highest metastatic potential when compared to those from sun-exposed sites. Tumors more than 2 cm in diameter are 3 times as likely to metastasize compared to smaller tumors. Tumors more than 4 mm in depth or extending down to the subcutaneous tissue are more likely to recur and metastasize compared to thinner tumors. Poorer prognosis is associated with less well differentiated tumors, and tumors arising in patients who are immunosuppressed.