What are cutaneous horns?
Cutaneous horns (cornu cutaneum) are hard conical projections from the skin, made of compact keratin. They are so named as they resemble an animal’s horn. They arise from benign, premalignant or malignant skin lesions.
Who gets them?
- Cutaneous horns are more common in older patients, with the peak incidence in those between 60 and 70.
- They are equally common in males and females, although there is a higher risk of the lesion being malignant in men.
- They are more common in people with fairer skins (skin phototype I and 2).
What causes cutaneous horns?
Around half of horns have a benign base, and half are premalignant or malignant. The most common lesions are seborrhoeic keratosis (degenerative), viral warts (due to human papillomavirus), solar (actinic) keratosis and well-differentiated squamous cell carcinoma (associated with exposure to the sun and other sources of UV radiation).
Clinical features of cutaneous horns
- Cutaneous horns generally present as curved hard yellow brown horns.
- They can be surrounded by normal skin or have a border of thickened skin.
- The side of the horn may be terrace-like with horizontal ridges.
- The base of the horn may be flat, protruding, or like a crater.
- Inflammation may be present, due to recurrent injury.
- Typically, the horn is taller than twice the width at the base.
- It may vary from a few millimetres to several centimetres in size.
- Giant horns exist – the largest described is a 76 year old Parisian woman named Madame Dimanche (Widow Sunday) in the 19th century, who grew a 25cm horn from her forehead
- Cutaneous horns are usually singular, but can be multiple.
- They can occur anywhere on the body, but are more common on sun-exposed areas especially the head and ears, back of hands and forearms.
- They may also occur on the chest, neck, shoulder and penis.
Cutaneous horns are usually asymptomatic, however as they are protuberant, they can be injured causing pain and inflammation.
Worrying features suggestive of malignancy
Whilst no certain features can confidently confirm or exclude malignant lesions, malignant lesions are more common in older patients and in males compared to females. Squamous cell carcinoma is also likely if the horn has the following features:
- Large size
- Induration at the base
- Anatomic site on the nose, ears, backs of hands, scalp, forearms, face and penis
- Wide base or low height to base ratio
- Redness at the base of the horn base
- Lack of terrace formation, due to rapid unorganised growth
Diagnosis and investigation of cutaneous horn
- A cutaneous horn is diagnosed by its clinical appearance.
- Histological examination of the horn base is crucial to rule out malignancy, as there are no certain clinical features that can definitively distinguish benign lesions from skin cancer.
- The lesion is usually completely removed surgically (excision biopsy). In some cases, a deep partial biopsy is taken to establish the diagnosis.
On histology, there is thickening of the stratum corneum (the top layer of the skin) or hyperkeratosis. Orderly horizontal parallel layers of keratin are associated more with benign lesions. Rapidly growing malignant lesions exhibit a more erratic growth. Acanthosis (thickening of the epidermis) is often noted. The base of the lesion shows features of the underlying lesion.
|Benign||Premalignant or malignant|
Treatment of cutaneous horn
Cutaneous horns are usually excised with appropriate margins, dependent of the nature of the lesion.