Invasive squamous cell carcinoma: a comparison of tumors with or without horn presentation based on age, sex, anatomic site, tumor diameter, depth of invasion, and grade of differentiation in 1,666 cases

INTRODUCTION Invasive squamous cell carcinoma (SCC) may present clinically with or without a horn. OBJECTIVE To compare invasive SCC with or without horn presentation by anatomic site, tumor diameter, depth, and grade of differentiation. MATERIALS AND METHODS The above characteristics of invasive SCC with or without horns were compared using a logistic regression model adjusted for potential confounders. RESULTS There were 7.0% horns (n 116) and 93.0% nonhorns (n 1,550) in 1,666 cases. The median tumor diameter was 6 mm for horns, and 8 mm for nonhorn cases, p <.001. The median depth of invasion was 0.8 mm for horn cases and 1.3 mm for nonhorns, p <.001. Most cases were well-differentiated SCC for both horns (n 102, 87.9%) and nonhorns (n 1,265, 81.6%) p .07. Horn cases had a borderline significant shift to well differentiation with moderate differentiation in 11.2% of cases (n 13) and poor differentiation in 0.9% (n 1). CONCLUSION Horns presented on invasive SCC with reduced tumor diameters and reduced invasion depths compared to nonhorns. Horns presenting on invasive SCC were usually well differentiated. However, moderate and even poor differentiation can occur within a horn base.