Ultrasound Characteristics of Keratoacanthoma: Differentiation From Well-Differentiated Cutaneous Squamous Cell Carcinoma.

Objective: This study aims to describe the ultrasound characteristics of keratoacanthoma (KA), providing valuable insights for non-invasive diagnosis and differentiation from well-differentiated cutaneous squamous cell carcinoma (wcSCC).

Methods: Ultrasound characteristics of 16 KA and 13 wcSCC conformed by surgical pathology were retrospective analyzed.

Results: KA patients were younger (mean age 63.13 years) compared with wcSCC patients (mean age 76.23 years). Ultrasound characteristics revealed that KA lesions were generally smaller, more frequently domed-shaped (87.50 vs 38.46%), exophytic (93.75 vs 30.77%), and well-defined (93.75 vs 53.85%) compared with wcSCC. Both lesion types predominantly showed hypoechoic internal echoes and inhomogeneous echotexture. The prevalence of hyperechoic superficial area was notably high in both groups (93.75 vs 84.62%), precluding the reliable use of this feature as a discriminatory marker between these two distinct neoplastic entities. KA lesions were mostly confined to the epidermis and superficial dermis (87.50%), while wcSCC cases frequently infiltrated into the subcutaneous fat layer (84.62%). Color Doppler imaging demonstrated higher vascularity in wcSCC lesions, with 61.5% showing Grade 3 flow, compared with KA lesions, where 62.5% exhibited Grade 2 flow.

Conclusions: High-frequency ultrasound reveals distinct ultrasound characteristics differentiating KA from wcSCC, offering a promising non-invasive tool for preliminary diagnosis and treatment planning.