Keratoacanthoma is a rare benign epithelial tumor characterized by cyclic course and spontaneous involution. Giant, mushroom-shaped, and aggregated forms of keratoacanthoma are atypical, and are often characterized by unpredictable and aggressive course, making them clinically similar to squamous cell skin cancer. This article describes the emergence of a giant aggregated keratoacanthoma with underlying post-burn scar after chemical exposure in a 55-year-old male patient. The diagnosis was established histologically, and no signs of malignancy were identified. The tumor was constantly subjected to mechanical stimulation, and repeatedly recurred even after radical surgical treatment. Tumor growth was followed by ulceration and bleeding. There was a positive clinical effect of ablation using CO2 laser, which resulted in partial tumor regression.