Snapshot A 74-year-old man presents to the dermatologist’s office for his annual total body skin exam. His past medical history is significant for multiple actinic keratoses, previously treated with cryotherapy. At this visit, he points to a larger lesion on his ear, complaining that it grew back after last year’s cryotherapy. A shave biopsy was done and pathology reveals malignant cells invading the dermis. He is scheduled for an excision. Introduction Invasive primary skin malignancy arising from keratinocytes of skin or mucosa Keratoacanthoma is a variant of low-grade squamous cell carcinoma grows rapidly and regresses spontaneously Bowen disease is a kind of cutaneous squamous cell carcinoma in situ that usually appears well-demarcated scaly patch or plaque often erythematous; however, can be pigmented or skin colored Epidemiology Common in fair-skinned individuals Common in elderly patients 2nd most common form of skin cancer (first is basal cell carcinoma ) Major risk factor = significant sun exposure (damage to keratinocytes) actinic keratosis actinic cheilitis Other risk factors immunosuppression (similar to treatment for organ transplant) arsenic exposure old scars or burns xeroderma pigmentosum ionizing radiation ETIOLOGY Pathogenesis typically develop from precursor actinic keratoses, but may arise de novo slow-growing malignancy metastases are rare Presentation Symptoms typically asymptomatic, but may be tender especially if ulcerated Physical exam from actinic keratosis red, poorly defined base with adherent yellow or white scale de novo sharply defined smooth, dull, red, dome-shaped nodule crusted center frequently ulcerates frequently on sun-exposed areas face, neck, hands, ears common on lower lips lesions often against a background of sun-damaged skin atrophy, telangiectasias, blotchy hyperpigmentation STUDIES Diagnosis by skin biopsy atypical keratinocytes and malignant cells invasion into dermis keratin “pearls” on histology Differential Actinic keratosis Actinic cheilitis Treatment Prevention sun avoidance sunscreen use Wide local surgical excision with histologic confirmation of negative margins Radiation if surgery is not an option Complications Potential recurrence if immunosuppressed Prognosis If treated, very excellent prognosis Lesions on lip, ear, or scalp may be more aggressive