Squamous Cell Carcinoma of the Skin

Essentials of Diagnosis

• Nonhealing ulcer or warty nodule

• Skin damage due to long-term sun exposure

• Common in fair-skinned individuals and in organ transplant recipients and other immunosuppressed patients

General Considerations

• Squamous cell carcinoma (SCC) usually occurs subsequent to prolonged sun exposure on exposed parts in fair-skinned individuals who sunburn easily and tan poorly

• It may arise from an actinic keratosis

• The lesions appear as small red, conical, hard nodules that occasionally ulcerate

• Diagnosis is made by biopsy

• Can be treated in situ with

  • Imiquimod

  • 5-fluorouracil (in similar dosing as for superficial BCC)

  • Curettage

  • Electrodessication

• Preferred treatment for invasive SCC is excision or Mohs micrographic surgery

• Mohs micrographic surgery is recommended for

  • High-risk lesions (lips, temples, ears, nose)

  • Recurrent tumors

  • Aggressive histologic subtypes (perineural or perivascular invasion)

  • Large lesions (greater than 1.0 cm face, > 2.0 cm trunk or extremities)

  • Immunosuppressed patients

  • Lesions developing within a scar

  • Tumors arising in the setting of genetic diseases

Follow-Up

• Follow-up for squamous cell carcinoma must be more frequent and thorough than for basal cell carcinoma, starting at every 3 months, with careful examination of lymph nodes for 1 year, then twice yearly thereafter

• Multiple SCCs are very common on the sun-exposed skin of organ transplant patients because of the patient's immunosuppressed state; the tumors begin to appear after 5 years of immunosuppression

• Other forms of immunosuppression that may also increase skin cancer risk and be associated with more aggressive skin cancer behavior

  • Allogeneic hematopoietic stem cell transplants

  • Chronic lymphocytic leukemia (and small lymphocyte lymphoma)

  • HIV/AIDS

  • Chronic iatrogenic immunosuppression

• Voriconazole appears to increase the risk of development of SCC, especially in lung transplant patients

Complications

• In actinically induced SCCs, rates of metastasis are estimated from retrospective studies to be 3–7%

• SCCs of the ear, temple, lip, oral cavity, tongue, and genitalia have much higher rates of recurrence or metastasis and require special management

• Patients with multiple squamous cell carcinomas (especially > 10) have higher rates of local recurrence and nodal metastases

Prognosis

• Tumor aggressiveness correlates with lesion size, duration, location, origin, and degree of anaplasia

• Tumors of the scalp, eyelids, nose, ears, and lips invade subcutaneous tissues and have a greater risk of subclinical tumor extension

Prevention

• Sun protection and avoidance

When to Refer

• There is a question about the diagnosis

• Recommended therapy is ineffective

• Specialized treatment is necessary