Anatomic location of basal cell carcinomas may favor certain histolgic subtypes

Background: Differences in age, site, and subtype exist in basal cell carcinoma (BCC). Objective: To evaluate whether an independent association exists between the anatomic location and the histologic subtype of BCC. Materials and Methods: A series of 3,254 BCCs was examined. The location was the head/neck (n = 1,766), limbs (n = 362), trunk (n = 1,113), or genitals (n = 13). Subtype was classified as superficial, nodular, micronodular, morpheic-infiltrative, or fibroepithelial. Results: Prevalence of BCCs on the head/neck or chest/abdomen increased with age (p < .001). The prevalence of superficial subtype decreased with age (p < .0001), whereas the prevalence on nodular subtype increased (p < .0001). Subtype was associated with location (p < .0001). The prevalence of superficial subtype was lower among BCCs on the head/neck than other locations (24.9% vs 64.4%, OR 0.18, 95% CI 0.16-0.21). The prevalence of nodular or morpheic/infiltrative subtype was higher among BCCs on the head/neck than other locations, that is, 57.1% versus 29.2%, OR 3.23, 95% CI 2.79 to 3.74 (nodular) and 16.1% versus 4.0%, OR 4.56, 95% CI 3.42 to 6.08 (morpheic/infiltrative). Conclusion: Anatomic location and subtype of BCC were associated with age, but the anatomic location was the only independent predictor of histologic subtype. Although a bias by referral patterns may not be excluded, the results suggest that the anatomic location may favor the development of particular BCC subtypes.