Anatomic location of Basal cell carcinomas may favor certain histologic subtypes

Differences in age, site, and subtype exist in basal cell carcinoma (BCC).

To evaluate whether an independent association exists between the anatomic location and the histologic subtype of BCC.

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.

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).

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.