ESSENTIALS OF DIAGNOSIS
Pearly papule, erythematous patch > 6 mm, or nonhealing ulcer in sun-exposed areas (face, trunk, lower legs).
History of bleeding.
Fair-skinned person with a history of sun exposure (often intense, intermittent).
Basal cell carcinomas are the most common form of cancer. They occur on sun-exposed skin in otherwise normal, fair-skinned individuals; ultraviolet light is the cause. Basal cell carcinomas can be divided into clinical and histologic subtypes, which determine both clinical behavior and treatment. The clinical subtypes include superficial, nodular, pigmented, and morpheaform. The histologic subtypes include superficial, nodular, micronodular, and infiltrative. Morpheaform, micronodular, and infiltrative basal cell carcinomas are not amenable to topical therapy or electrodesiccation and curettage and typically require surgical excision or Mohs micrographic surgery. Because a second basal cell carcinoma develops in up to half of patients, skin examination is required at least yearly to detect new or recurrent lesions. Nicotinamide, 500 mg orally twice daily, can decrease the rate of development of basal cell carcinomas by 20% in high-risk groups.
The most common presentation is a papule or nodule that may have a central scab or erosion (Figure 6–31) (eFigure 6–82). Occasionally the nodules have stippled pigment (pigmented basal cell carcinoma). Intradermal nevi without pigment on the face of older White individuals may resemble basal cell carcinomas. Basal cell carcinomas grow slowly, attaining a size of 1–2 cm or more in diameter, usually only after years of growth (eFigure 6–83). There is a waxy, “pearly” appearance, with telangiectatic vessels easily visible (eFigure 6–84) (eFigure 6–85). It is the pearly or translucent quality of these lesions that is most diagnostic, a feature best appreciated if the skin is stretched (eFigure 6–86). On the back and chest, basal cell carcinomas appear as reddish, somewhat shiny, scaly thin papules or plaques. Morpheaform basal cell carcinomas are scar-like in appearance. Basal cell carcinomas are more common and more likely to recur in immunosuppressed patients, including those with non-Hodgkin lymphoma and those who have undergone solid organ or allogeneic hematopoietic stem cell transplantation.
Pearly nodular basal cell carcinoma on the face of a 52-year-old woman present for 5 years. (Used, with permission, from Richard P. Usatine, MD, in Usatine RP, Smith MA, Mayeaux EJ Jr, Chumley HS. The Color Atlas and Synopsis of Family Medicine, 3rd ed. McGraw-Hill, 2019.)
Basal cell carcinoma. (Reproduced, with permission, from Bondi EE, Jegasothy BV, Lazarus GS [editors]. Dermatology: Diagnosis & Treatment. Originally published by Appleton & Lange. Copyright © 1991 by The McGraw-Hill Companies, Inc.)
Superficial basal cell carcinoma. (Used, with permission, from Lindy Fox, MD.)