Correlation of embryonic fusion planes with the anatomical distribution of basal cell carcinoma

BACKGROUND The clinical relevance of the anatomic distribution of basal cell carcinoma is not completely understood. Embryonic fusion planes-the regions of mesenchymal migration and fusion of the five primordial facial processes during the 5th to 10th weeks of human development-have been implicated in the pathogenesis of basal cell carcinoma. OBJECTIVE This study sought to examine the predilection of midfacial basal cell carcinoma for cutaneous anatomical sites correlated to embryonic fusion planes. METHODS AND MATERIALS Using archived digital images and a detailed anatomic diagram, cases of basal cell carcinoma were coded according to their specific location and were aggregated into two anatomic domains according to their correlation to embryonic fusion planes. The relative tumor densities were calculated. RESULTS Of the 1,457 cases examined, 859 were located in the midface. Thirty-five percent of the midfacial lesions were located on the domain correlated to embryonic fusion planes, which represented 11.3% of the total surface area of the midface. The relative tumor density of lesions in the fusion plane domain was 3.06 compared to 0.74 for the remaining lesions (p < .001). CONCLUSIONS Although there is no consensus about the importance of anatomic location in the pathogenesis of basal cell carcinoma, these data indicate that, after adjusting for surface area, basal cell carcinoma was more than four times more likely to occur on an embryonic fusion plane than on other regions of the midface. These data support the possibility of an embryologic role for the pathogenesis of basal cell carcinoma.