ABSTRACT
BIOLOGY n Tumors originate from the pluripotential epithelial cells of epidermis and hair follicles (basal
keratinocytes) at the dermoepidermal junction.
TYPES OF BCC1,4,12-15 There are 26 identified subtypes that follow particular histologic patterns12 (Fig. 15-1). Mixed patterns are found in 38.5% of cases. n Nodular
• Most common histologic type: 50%-60% • Well-defined borders, flesh-colored, pearly nodule with overlying telangiectasias • May be ulcerated: Central ulcer surrounded by rolled border; historically called rodent ulcer
n Superficial spreading • 9%-15% of BCCs, second most common type • Located in epidermis, no dermal invasion • Flat, pink, scaly patches with ulcerations and crusting, usually multiple, on trunk • Often mistaken for fungal infection, actinic keratosis, psoriasis, or eczema
n Micronodular • 15% of BCCs • Small rounded nodules of tumor the size of hair bulbs
n Infiltrative • 7% of BCCs • Opaque yellow-white color, blends with surrounding skin • Tumor islands of variable size with jagged configuration
n Pigmented • 6% of BCCs • Pigmentation from melanin • Often confused with melanoma
n Morpheaform (sclerosing or fibrosing) • 2%-3% of BCCs, most aggressive • Typically described by patients as an “enlarging scar” without history of trauma • Usually an indurated, flat, or slightly elevated papule or plaque with white to yellow scarlike
appearance • Rarely ulcerates • High incidence of positive margins after excision
Fig. 15-1 Histologic types of basal cell carcinoma.
