Shedding New Light on Cutaneous Horns: A Comprehensive Review and Pitfall of Management

A cutaneous horn, also known as cornu cutaneum, is an uncommon protuberance of highly compacted keratinous material from the stratum corneum, resembling an animal horn. Although the cause and pathogenesis of these lesions were long misunderstood, cutaneous horns are now generally recognised to be reactive skin growths that can result from a variety of infectious, malignant, pre-malignant, and benign conditions. Most cutaneous horns are benign, but approximately 16%-20% are malignant, with squamous cell carcinoma being the most common malignant underlying aetiology. As the identification of the underlying aetiology necessitates microscopic examination of the base of the cutaneous horn, a major potential pitfall in the diagnosis and management of these lesions lies in the use of improper biopsy technique, which leads to inadequate sampling and failure to correctly identify the underlying aetiology of the lesion. This focused and up-to-date comprehensive review addresses the clinical presentations, epidemiology, aetiology/pathogenesis, histopathology, and differential diagnosis for cutaneous horns. In addition, we provide an overview of the many conditions that may underlie cutaneous horns and the management/treatment of cutaneous horns, including a discussion of proper excision/biopsy technique. Our review aims to enhance understanding and shed light on some of the potential pitfalls in the diagnosis and treatment of cutaneous horns, with the goal of improving outcomes for patients presenting with this condition.