Table 1.

Comparison of non-melanoma and melanoma cancers

Variable	Keratinocyte (non-melanoma)		Melanoma
	Squamous cell	Basal cell
Cell type	Squamous cells	Basal cells	Melanocytes
Epidemiology	Elderly men	Elderly men	Aged 20+ men and women
Risk factors	UV light exposure, age, lighter skin, immunosuppression, tobacco, albinism, xeroderma pigmentosum	UV light exposure, age, lighter skin, sunburn	UV light exposure, family history, freckles, moles, >5 atypical nevi, age, lighter skin, red hair, tanning bed use
Precursor lesion	Actinic keratoses, Bowen's disease (in situ)	De novo	Dysplastic nevi, lentigo maligna
Gross appearance	Erythematous, scaly patch or plaque	Pearly nodule or scaly, erythematous, flat lesion	Characterized by ABCDEs (asymmetry, border, color, diameter, evolution), initially horizontal then vertical growth
Histopathology	Pleomorphic nuclei, keratinization of the epidermis (in situ) or dermis (invasive)	Basaloid cell nests, peripheral palisading, necrotic keratinocytes, spindle cell stroma	Pathology varies based on subtype
Prognosis	Risk of metastasis, mortality > BCC	Low mortality, less likely to metastasize	Most severe, prognosis is proportional to thickness (Breslow's depth)
Treatment (depends on metastasis)	Surgery, XRT, chemotherapy	Surgery, cryotherapy, PDT, topicals, chemotherapy	Surgery, XRT, chemotherapy, immunotherapy

BCC indicates basal cell carcinoma; PDT, photodynamic therapy; UV, ultraviolet; XRT, radiation.