Dermatofibroma

A 33-year-old woman had a facial lesion (Figures 1 and 2) that seemed to "come out of nowhere," but it was months before she sought medical attention. She was certain that the duration was months, not years, but could not date the exact onset.

[FIGURES 1-2 OMITTED]]

The lesion was asymptomatic except for its prominence and aesthetics. The patient had tried cutting the lesion off several times, but it regrew each time. She was married, monogamous by history, not pregnant, had no major underlying medical conditions, and had no personal or family history of skin malignancy. The remainder of the skin examination was normal.

* WHAT IS YOUR DIAGNOSIS?

* WHAT WOULD BE YOUR MANAGEMENT PLAN?

* DIAGNOSIS: CUTANEOUS HORN

Cutaneous horn, also referred to as cornu cutaneum, is a clinical (morphologic) diagnosis, not a precise pathologic diagnosis. It describes an asymptomatic, projectile, conical, dense, hyperkeratotic lesion that resembles the horn of an animal.

Cutaneous horns can arise from a variety of primary underlying pathologic processes, including benign, premalignant, and malignant lesions. Thus, the important issue when confronted with a cutaneous horn is determining the causative pathologic process. Therefore, for treatment, most authors stress surgical excision with attention to removing the base of the specimen for histopathologic examination. (1-4)

Cutaneous horns may vary considerably in size and shape. Most are a few millimeters in length, but there are reports of some measuring up to 6 cm in length. They may be perpendicular or inclined in relation to the underlying skin. They usually occur singly and may grow slowly over decades. (2,4)

Cutaneous horns are more common in older and white individuals, although they have been reported in children and African Americans. (5) The higher prevalence in older and light-skinned individuals is secondary to the fact that many cutaneous horns are caused by cumulative sun damage over many years, leading to actinic keratoses and nonmelanoma skin cancer.

Differential diagnosis

The differential diagnosis of the underlying causes of cutaneous horns is extensive. Some causes are listed in the Table; common ones include actinic keratoses (25%-35% of patients with cutaneous horns), verruca vulgaris (15%-25%), and cutaneous malignancies (15%-40%). (1)

Features that have been reported to increase the chance of an underlying malignancy include older age, male sex, lesion geometry (either a large base or a large height-to-base ratio), and presence on a sun-exposed location (face, pinnae, dorsal hands and forearms, scalp). More than 70% of cutaneous horns with underlying premalignant or malignant lesions are found on these sun-exposed areas. (3,6) Additionally, cutaneous horns on these locations are twice as likely to harbor underlying premalignant or malignant lesions. (6) Of patients with malignancies underlying their cutaneous horns, up to one third have a history of skin malignancy. (7)

* TREATMENT OPTIONS

Cryosurgery

Some textbooks list cryosurgical therapy as an option. (8) If there were a clearly benign pre-existing underlying dermopathy, such as verruca vulgaris or molluscum contagiosum, cryosurgery might be considered. However, cryosurgery is destructive; it does not preserve a specimen for pathologic examination. Because cutaneous horns have a 15% to 40% chance of underlying malignancy, (1,4) it is difficult to recommend cryosurgical destruction without an initial biopsy-proven diagnosis.

Punch biopsy

In this patient, a 3-mm excisional punch biopsy was performed using a punch-to-ellipse technique. The skin is stretched parallel to the skin lines as the punch biopsy is performed. As the skin relaxes after removal of the punch instrument, an elliptical defect remains, enhancing cosmesis of the repair. Especially for a convex facial surface (which heals less well cosmetically than concave facial surfaces), this technique was believed to offer the potential for a better long-term cosmetic result.

In this case, a shave biopsy would have been a good option for both diagnosis and treatment. If the pathology from a punch biopsy or shave biopsy turned out to demonstrate an underlying skin cancer, then a fusiform excision would be needed to provide adequate surgical margins for the definitive treatment.

* RESULTS OF HISTOLOGIC EXAM

With this patient, histologic examination revealed that the underlying condition was verruca vulgaris, or the common wart. Several months after removal of the cutaneous horn, the patient could not locate the surgical site, a cosmetically acceptable result to her and her physician (Figure 3).

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ACKNOWLEDGMENTS

The author would like to acknowledge the unfailing cooperation and expert assistance of the St. Vincent Mercy Medical Center library staff. The author has no conflicts of interest to report.

REFERENCES

(1.) Gould JW, Brodell RT. Giant cutaneous horn associated with verruca vulgaris. Cutis 1999; 64:111-112.

(2.) Kastanioudakis I, Skevas A, Assimakopoulos D, Daneilidis B. Cutaneous horn of the auricle. Otolaryngol Head Neck Surg 1998; 118:735.

(3.) Korkut T, Tan NB, Oztan Y. Giant cutaneous horn: a patient report. Ann Plast Surg 1997; 39:654-655.

(4.) Stavroulaki P, Mal RIL Squamous cell carcinoma presenting as a cutaneous horn. Auris Nasus Larynx 2000; 27:277-279.

(5.) Souza LN, Martins CR, de Paula AM. Cutaneous horn occurring on the lip of a child. Int J Paediatr Dent 2003; 13:365-367.

(6.) Akan M, Yildirim S, Avci G, Akoz T. Xeroderma pigmentosum with a giant cutaneous horn. Ann Plast Surg 2001; 46:665-666.

(7.) Spira J, Rabinovitz H. Cutaneous horn present for two months. Dermatol Online J 2000; 6:11.

(8.) Benign skin tumors (Chapter 20). Cutaneous horn. In: Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 4th ed. St. Louis, Mo: Mosby; 2004:706.

(9.) Khaitan BK, Sood A, Singh MK. Lichen simplex chronicus with a cutaneous horn. Acta Derm Venereol 1999; 79:243.

(10.) Agarwalla A, Agrawal CS, Thakur A, et al. Cutaneous horn on condyloma acuminatum. Acta Derm Venereol 2000; 80:159.

Correspondence: Gary N. Fox, MD, 2200 Jefferson Avenue, Toledo, OH 43624. E-mail: foxgary@yahoo.com.

Gary N. Fox, MD

Mercy Health Partners Family Practice Residency Program, Toledo, Ohio

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