Cutaneous Horn Revisited: A Woman With a Verruca Vulgaris-Associated Cornu Cutaneum

Abstract

A cutaneous horn, sometimes referred to as cornu cutaneum, is a projection arising on the skin due to an overgrowth of the epidermal stratum corneum. This lesion is a clinical presentation of an underlying skin tumor. A woman with a verruca vulgaris-associated cutaneous horn is described. Cutaneous horns are often solitary and appear most commonly on the face, ears, and the dorsum of the hands of older patients. The most frequent tumors associated with cutaneous horns include actinic keratoses and seborrheic keratoses; however, cutaneous horns have also been observed overlying other benign and malignant tumors. In conclusion, a cutaneous horn is a common clinical feature; however, the diagnosis of the underlying skin lesion requires a biopsy that permits adequate microscopic evaluation of the associated tumor.

Keywords: actinic; carcinoma; cutaneous; horn; keratoacanthoma; keratosis; seborrheic; squamous cell carcinoma; verruca; vulgaris.

Figure 1. Clinical presentation of verruca vulgaris-associated cutaneous horn

Distant (A) and closer (B) views of a verruca vulgaris (red arrow) associated with overlying cutaneous horn (black arrow) on the left forearm of an 81-year-old woman.

Figure 2. Pathologic features of a cutaneous horn associated with a verruca vulgaris

Distant (A) and closer (B, C, and D) views of verruca vulgaris with an overlying cutaneous horn. There is massive thickening of the stratum corneum (black bracket) showing hyperkeratosis consisting of compact keratin with retained cell nuclei (parakeratosis) (A); these are the pathologic features of a cutaneous horn. The cup-shaped lesion shows prominent thickening of the epidermis (blue bracket demonstrating acanthosis) (A and C). There is also inward pointing of the epidermis at the lateral edge (black circle) (A and B); in this same area, there are dilated blood vessels in the dermal papillae (black arrows) and an elongated epidermal rete ridge (white arrow). In the thickened stratum granulosum (red circle) (A, C, and D), there are halo cells (red arrows showing koilocytes) (D) indicative of human papillomavirus infection; these are the pathologic features of a cup-shaped verruca vulgaris.