Supplementary Material for: A case of generalized Bowen's disease accompanied generalized seborrheic keratosis with literature review

Background: Bowen's disease (BD) and seborrheic keratosis (SK) share certain common pathogenic factors. However, the nature of their relationship remains controversial, particularly whether SK undergoes malignant transformation into BD or if their coexistence represents a "collision tumor" phenomenon.
Objective: This article aims to explore the relationship, diagnosis, and treatment of BD and SK by presenting a case of generalized Bowen's disease accompanied by generalized seborrheic keratosis, supplemented with a review of relevant literature.
Methods: A 70-year-old male patient presented with a 14-year history of "red patches distributed across the body." Dermoscopic examination of the red plaques revealed a red background with uniformly distributed glomerular vessels and scattered yellow and white scales. The brown plaques demonstrated a homogeneous brown pattern with yellowish-white scales, occasionally displaying light red homogeneous structures and dotted or linear vessels. Histopathological analysis indicated irregular epidermal hyperplasia, hyperkeratosis, parakeratosis, and acanthosis. The epidermal cells exhibited disordered arrangement, significant atypia, and visible mitotic figures, while the basal cell layer remained intact. Inflammatory cell infiltration was observed in the dermis.
Results: The patient was diagnosed with generalized Bowen's disease accompanied by generalized seborrheic keratosis. Treatment included cryotherapy, oral Acitretin capsules, and topical Isotretinoin cream. The patient responded well to the treatment and remains under follow-up.
Conclusion: Clinicians should maintain a high index of suspicion for irritated or inflamed SK lesions, as they may harbor underlying Bowen's-like changes. Early recognition and appropriate management are crucial to ensure optimal outcomes.