Humans Can Also Have Horns!

Cutaneous horns:

·       Cutaneous horns are unusual keratinous skin tumors with the appearance of horns, or sometimes of wood or coral. Formally, this is a clinical diagnosis for a "conical projection above the surface of the skin.

·       "They are usually small and localized but can, in very rare cases, be much larger.

·        Although often benign, they can also be malignant or premalignant.

·       The lesion at the base of the keratin mound is benign in the majority of cases. Malignancy is present in up to 20% of cases, with squamous-cell carcinoma being the most common type.

·       The incidence of squamous-cell carcinoma increases to 37% when the cutaneous horn is present on the penis. Tenderness at the base of the lesion oftewn suggests the presence of a possible underlying squamous-cell carcinoma.

·       A cutaneous horn is 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).

·       Around half of horns have a benign base, and half are premalignant or malignant. The most common underlying lesions are seborrhoeic keratosis, viral warts (due to human papillomavirus), actinic keratosis, and well differentiated squamous cell carcinoma (associated with exposure to the sun and other sources of UV radiation).

Appearance:

·       A cutaneous horn generally presents as a straight or curved, hard, yellow-brown projection from the skin.
It can be surrounded by normal skin or have a border of thickened skin.The side of the horn may be terrace-like or oyster shell-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 horn from her forehead that was 25-cm long.
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.

Symptoms:

·      Cutaneous horns are usually asymptomatic. They can be injured causing pain and inflammation.

Associated conditions and problems:

·      There are many other conditions that doctors associate with cutaneous horns. The conditions and complications range from benign to cancerous.

·      Benign conditions associated with cutaneous horns include:

• pigmented growths on the skin called nevuses
• harmless, warty growths on the skin known as seborrhoeic keratosis
• viral warts not related to HPV
• viral skin infections, such as molluscum contagiosum
• psoriasis

·         While these conditions are not cancerous, some of them may require medical treatment. These conditions include the viral skin infections and psoriasis.

More serious conditions associated with cutaneous warts include:

• squamous cell carcinoma or Bowen’s disease
• basal cell carcinoma
• melanoma (very rarely)
• intraepidermal carcinoma
• arsenical keratosis

Keratoacanthoma:

Another growth, keratoacanthoma, is a lesion that resembles a small volcano. It can grow up to 2 centimeters (cm) in diameter in sun-damaged skin. It may start as a small pimple, then develop over a few months, before shrinking.

A doctor may recommend surgery to reduce the risk of it becoming malignant, as it can resemble squamous cell carcinoma (SCC).

·         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 excised. In some cases, a deep partial biopsy is taken to establish the diagnosis.

On histology, there is thickening of the stratum corneum or hyperkeratosis. Orderly horizontal parallel layers of keratin are associated more with benign lesions. Rapidly growing malignant lesions exhibit a more erratic growth. Acanthosis is often noted. The base of the lesion shows features of the underlying lesion.

Cutaneous horn: A mask to underlying malignancy in mouth

A59-year-old male reported with a chief complaint of a growth on the left side of upper lip. The lesion had been present for the last 6 months with gradual increase in size. Previously, the patient had undergone surgical excision of the lesion twice in the same area from an outside clinic only to notice it regrow again. He had the habit of smoking cigarettes for the past 25 years, around 20 cigarettes per day. The patient also gave a history of anemia for the past 1 month and was taking folic acid medication regularly. No other signs and symptoms were present.

On close clinical examination, an exophytic growth was seen on the left corner of upper lip. The growth was about 1.5 cm in length and was brown. On palpation, the growth was firm to hard in consistency and was slightly tender. Intraoral examination revealed a grayish-white patch on the left commissural mucosa and the dorsum of tongue measuring about 3 cm × 1 cm in dimension. Both the white patches were nontender and nonscrapable in nature. Hard tissue examination revealed several missing teeth 

 The histological sections revealed hyperkeratotic stratified squamous epithelium with underlying connective tissue. The epithelium exhibited acanthosis, spongiosis, hyperkeratosis and broad rete pegs with pushing margins along with parakeratinized keratin plugging. The underlying connective tissue exhibited mild inflammatory cell infiltration, areas of hemorrhage and muscle fibers bundles in cross sections .The superficial layer of epithelium in one area showed exuberant keratinization in concentric layers forming a cutaneous horn .The final diagnosis was given as cutaneous horn with underlying verrucous carcinoma. Histopathologic sections from the tissue adjacent to the cutaneous horn showed features of mild-to-moderate dysplasia.

Cutaneous Horn of the Eyelid

A 19-year-old male patient, resident in a the rural area, was admitted to the Ophthalmology Clinic for a solitary firm horn on the lower eyelid, which had gradually progressed over the course of two months. One year before, the patient noticed a focal swelling of the inferior eyelid treated empirically, on which the cone shape growth developed progressively. The patient’s medical and ocular history was not significant.

The clinical examination revealed a solitary cone shape hyperkeratotic growth mesuring 1.0/0.6 cm in size, with an inflamed nodular base, located in the middle 1/3rd of the inferior right eyelid. There was no regional lymphadenopathy. The clinical diagnosis was that of solitary inferior right eyelid cutaneous horn. The lesion was excised completely with local anesthesia, and the defect was closed by sliding the skin of the inferior eyelid and sutured with Vicryl .

References:

Mantese SA, Diogo PM, Rocha A, Berbert AL, Ferreira AK, Ferreira TC. Cutaneous horn: a retrospective histopathological study of 222 cases. An Bras Dermatol. 2010 Mar-Apr 2010;85(2):157-163.

Yu RC, Pryce DW, Macfarlane AW, Stewart TW. A histopathological study of 643 cutaneous horns. Br J Dermatol. May 1991;124(5):449-452.

Pyne J, Sapkota D, Wong JC. Cutaneous horns: clues to invasive squamous cell carcinoma being present in the horn base. Dermatol Pract Concept 2013;3(2):2

Copcu E, Sivrioglu N, Culhaci N. Cutaneous horns: are these le¬sions as innocent as they seem to be? World J Surg Oncol. 2004:3(2):18.

Cutaneous Horn – Medscape Reference