Giant Cutaneous Horn: Is It a Tip of An Iceberg? Two Case Reports and a Review of Literature

Abstract

Cutaneous horns are uncommon lesions which consist of proliferation of keratotic material resembling that of an animal horn. This lesion most commonly occurs in sun-exposed areas, particularly the face, ear, nose, forearms and dorsum of hands. The purpose of the study was to highlight the atypical presentation of squamous cell carcinoma as a giant cutaneous horn along with the review of literature. Case details were obtained from hospital records and clinical and histopathological findings were noted. Herein we report two cases of giant cutaneous horn associated with an underlying carcinoma presenting at an uncommon site. Both the patients were adults and had a chronic history of a skin lesion over the affected sites. Wide local excision was performed in both cases and histopathological examination confirmed the diagnosis of a cutaneous horn with a well differentiated squamous cell carcinoma at the base of the horn. Cutaneous horns are commonly associated with benign lesions and rarely with malignant conditions. It is imperative to biopsy the base of the horn to rule out any underlying malignancy. Proper surgical excision with adequate margins is the preferred treatment in case of an underlying malignancy.

Introduction

Cutaneous horns are also known as “Cornu cutaneum” by the Latin name [1]. Cutaneous horns are mostly associated with benign lesions (60%), but there are reports of its association with malignant and premalignant lesions [2]. Hereby, we report two cases of giant cutaneous horn to highlight the atypical presentation of squamous cell carcinoma and the need for its proper management. This is a second case in the world literature, of a giant cutaneous horn at the cheek with underlying squamous cell carcinoma, to the best of our knowledge.

Case Description and Results

Case 1

55-year-old male presented to our outdoor patient department with an exophytic growth over right side of cheek for 2–3 years. Patient had a past history of surgery over the same area but no documents were available. His radiological report (CT scan) showed presence of large exophytic heterogeneously enhancing soft tissue density lesion involving right upper and lower buccal space with its extension to overlying skin. Incisional biopsy was done from the base of the lesion and it revealed a well differentiated, squamous cell carcinoma. A Wide local excision of the lesion with adeqaute margins(r0) was acheived along with a modified neck dissection. Gross examination showed a giant cutaneous horn measuring 8 cm on the skin over the right side of cheek (Fig. 1a). Lower buccal mucosa revealed a whitish leukoplakic patch measuring 4.1 × 2.2 × 0.3 cm³. Histopathological examination revealed the horn showing extensive keratinization in concentric layers forming a cutaneous horn and the base of the horn revealed a superficially invasive, well differentiated, squamous cell carcinoma with 0.4 cm depth of invasion. All the dissected neck nodes were free of tumour. Patient was followed up for 2 years post surgery and is uneventful.

Fig. 1.

a Photograph of case 1  with giant cutaneous horn involving the right side of cheek. b gross photograph of the case 2 of giant cutaneous horn over the angle of mouth

Case 2

50 years old female presented with an exophytic growth over the left side of an angle of mouth (AOM) for 2 years. CT scan of local part revealed 41 × 21 × 15 mm sized heterogeneously enhanced soft tissue lesion involving the left side of AOM and adjacent part of lower lip. Incision biopsy from the base of the lesion was diagnosed as squamoproliferative lesion without dysplasia. Wide local excision of the lower lip with angle of mouth was performed. Grossly, a proliferative lesion was noted involving the mucosa and the skin  of the left side of AOM and part of lower lip along with  a 5 cm cutaneous horn (Fig. 1B). Microscopically tumour showed hyperplastic surface epithelium with keratinization. Base of horn confirmed the diagnosis of superficially invasive squamous cell carcinoma with 0.1 cm depth of invasion (Figs. 2,3). All submitted resection margins were free of tumour. Patient was followed up for two months with no complications.

Fig. 2.

Microscopic photograph shows extensive keratinization in concentric layers forming a cutaneous horn, 40x

Fig. 3.

Microscopic photograph of  underlying squamous cell carcinoma from Case 1,40x 

Discussion

Cutaneous horn is a clinical diagnosis which refers to a conical projection above the surface of the skin. It is organized in a shape of an animal horn, comprising of cohesive cornified keratin material [3]. Cutaneous horns externally resemble animal horns, but are histologically different from them [4]. Histologically animal horns are composed of superficial hyperkeratotic epidermis, dermis, and centrally well-formed bone, while a well-formed bone is not seen in human cutaneous horns [4].

A well-documented case of cutaneous horn reported in 1588 is of Mrs. Margaret Gryffith, an elderly Welsh woman. However, earliest observations were described by the London surgeon Everard Home in 1791 [3]. The first well documented case report with adequate histology of gigantic horn was reported by Farris from Italy [5]. The London surgeons Everard Home and his brother-in-law John Hunter are credited for the recognition of cutaneous horns as a medical disorder in the late eighteenth century [2].

These lesions are reported in the Caucasian and the Asian population and are rarely reported in the people of African descent [6]. This racial predilection is due to the relative protection of the pigmented skin from the ultraviolet sun rays. This also correlates with the racial distribution of other skin lesions that are related to actinic damage. Over 30% of these lesions are seen in the head and neck region [3]. Other sun-exposed areas of the body such as chest, neck, shoulders and dorsum of the hand also have the tendency to develop a cutaneous horn. Amongst the non-sun-exposed areas, this lesion has been reported at the lower lip mucosa, penis and nasal vestibule [7]. The angle of mouth is a comparatively rare site for the cutaneous horn and malignancies associated with them are even more uncommon.

The important issue is not the horn itself which is dead keratin, but rather the underlying condition, which could be benign, premalignant or malignant [8]. The term “cutaneous horn” does not indicate any specific pathological diagnosis. However, the base of the lesion can show a spectrum of lesions from benign to malignant. Underlying lesions include benign (seborrheic keratosis, viral warts, histiocytoma, inverted follicular keratosis, verrucous epidermal nevus, and molluscum contagiosum), premalignant (solar keratosis, and Bowen’s disease), or malignant (squamous cell carcinoma, rarely, basal cell carcinoma, metastatic renal carcinoma, granular cell tumor, sebaceous carcinoma, or Kaposi’s sarcoma). Hence, it becomes imperative to take a biopsy from the base of the horn, and for smaller lesions, surgical excision should be considered.

Size and shape of cutaneous horns can be variable, such as cylindrical, conical, pointed, transversely or longitudinally corrugated, or curved like a ram's horn [3]. Studies on parameters that are commonly associated with (pre)malignant base pathology have produced conflicting evidence with regard to age, sex and the shape of the lesion. Large cutaneous horns, particularly giant horns, are said to be commonly derived from a malignant base. [9].

Cutaneous horns with a wider base or a low height-to-base ratio were more likely to show either premalignant or malignant base pathology [9].

Cutaneous horns are most prevalent above 50 years of age, for both sexes and the average age for the occurrence of lesions in patients with premalignant and malignant lesions is around six years more than that of patients with benign alterations. Cutaneous horns with (pre)malignant base pathology were more common in males [9].

In a study  by Mir et al. [10] they histologically confirmed 3 out of 6 cases of cutaneous horn had underlying squamous cell carcinoma. In one largest study by Mentese et al. [11] they histologically studied 222 cases of cutaneous horn, confirmed 58.56% case had underlying premalignant and malignant lesion and within the group of malignant lesions, squamous cell carcinoma was found in 93.75% of cases. In a study by  Pyne et al. [12] Invasive SCC 34.4% (56/163) was the most common histopathology at the horn base. Copcu et al. [13] studied 11 cases of cutaneous horn, and they found two cases of squamous cell carcinoma, and one case of basal cell carcinoma, other 8 cases were benign. On the review of literature, we found 4 cases in the past have been reported to have a giant cutaneous horn at the lip with associated underlying malignancy.

Advanced age, Male gender, sun exposed lesion site and geometry of lesion are the factors which predispose to malignant or premalignant histopathology at the base of a cutaneous horn [2, 14]. Proper and adequate biopsy from the base of the lesion is advocated in such lesions to detect underlying malignancy, as the base will display features characteristic of the pathologic process responsible for the development of the horn. Though cutaneous horn can be treated by simple detachment and cauterization of the base, a full-thickness wide local excision with an adequate margin should be sent for histopathologic analysis, because of the frequent association of malignant/premalignant lesions at the base [2, 15].

Various case reports of giant cutaneous horn with underlying malignancy described in Table 1.

Table 1.

Reported cases of giant cutaneous horn with underlying carcinoma

Study	Age	Sex	Site	Histological diagnosis	Size of horn
Skoulkais et al. [16]	72	M	Vermilion of lower lip	Squamous cell carcinoma	3.5 cm
Akram et al. [17]	85	M	Temple	Squamous cell carcinoma	6.5 cm
Kumar et al. [2]	45	M	Buccal mucosa	Verrucous carcinoma	4 cm
Popadic [18]	76	F	Vermilion of lower lip	Squamous cell carcinoma	6.3 cm
Kneitz et al. [1]	90	M	Cheek	Squamous cell carcinoma	5 cm
Xu et al. [19]	86	M	Eyebrow	Squamous cell carcinoma	10 cm
Leelavathy et al. [20]	62	M	Angle of mouth	Verrucous carcinoma	7 cm
Piento-Almeido [21]	45	M	Lower lip	Squamous cell carcinoma	3 cm
Shahi et al. [15]	74	M	Pinna	Verrucous carcinoma	8 cm
Singh et al. [22]	52	F	Oral commissure	Verrucous carcinoma	3 cm

Conclusions

Giant cutaneous horns are rare exophytic lesions resembling the animal horn. Giant cutaneous horn at the cheek and the angle of mouth are an uncommon presentation. Site and size of lesion may predict the underlying malignant behavior. The fact that such lesions might harbor an underlying malignancy, emphasizes the need for a proper biopsy from the base of lesion and wide local excision with adequate margin clearance.

We are reporting these cases to highlight the atypical presentation of squamous cell carcinoma and the need for its proper management.