Seborrheic keratosis

Abstract

Seborrheic keratoses are superficial epithelial lesions. They are usually pigmented and often warty, but sometimes they appear as smooth papules. These lesions frequently occur on the face during middle and old age. We report an unusual case of a large seborrheic keratosis of the auricle. We also emphasize the importance of the differential diagnosis, and we discuss the treatment strategy for these usually benign but disfiguring tumors.

Introduction

A variety of skin lesions, including neoplasms, can be encountered on the auricle. Although most are benign, many are malignant or premalignant. (1) Benign tumors can usually be distinguished from malignant masses clinically and microscopically, although the specific diagnosis of all tumors requires microscopic examination.

Seborrheic keratoses are the most common tumors of the skin in older patients. Even though they are generally benign, they should still be differentiated from other tumors clinically and histologically. (1,2) Seborrheic keratosis should be included in the differential diagnosis of auricle lesions, but this fact has not been made adequately clear in the otolaryngologic literature. In this article, we describe the case of a patient who had a large seborrheic keratosis of the left auricle. We also discuss the differential diagnosis and the management of these lesions.

Case report

A 76-year-old woman came to the outpatient service at Venizelion Hospital in Crete with a 6-year history of a steadily growing, painless mass on her left auricle. Her history was remarkable for a mild case of systemic lupus erythematosus.

On physical examination, we observed a large, brown, warty mass that originated in the posterior portion of the helix (figure). Numerous smaller but similar lesions were arrayed on her face, neck, and forearms. Examination of the neck for enlarged cervical lymph nodes was negative.

Seborrheic keratosis was suspected, and a shave excision was performed. Pathologic analysis confirmed the diagnosis.

Discussion

The auricle is made up of many different types of tissue, each of which can give rise to one or more different types of tumor. The skin produces a wider variety of tumors than does any other organ. (1)

Clinically, benign tumors are usually characterized by slow or no growth. Microscopically, these tumors feature a well-organized cellular pattern. In addition to seborrheic keratoses, benign tumors of the auricle include senile keratoses, papillomas, keratoacanthomas, adenomas, and vascular tumors. Malignant tumors, of course, tend to grow and invade adjacent tissues. Common skin cancers include basal cell and squamous cell carcinomas, Kaposi's sarcomas, adnexal tumors, and cutaneous T-cell lymphomas. (3,4)

Seborrheic keratosis is a rather common benign epidermal proliferation. Its cause is unknown. (4) Most patients have multiple lesions, often distributed symmetrically; the number of lesions tends to increase with age. Seborrheic keratoses generally occur on the face, chest, back, abdomen, and extremities. The lesions are usually warty, but they occasionally appear as flat plaques, rarely larger than 3 cm in diameter. Their color ranges from light brown to black, and they normally have sharply delineated margins. In time, the surface of these lesions can become more elevated and more pigmented and can assume a more warty or rough appearance. (4) Some lesions are covered by a greasy scale. (1) Small pieces of the lesion can flake off with minor trauma, which can cause slight bleeding.

Seborrheic keratosis has a wide variety of histologic features, and these lesions are classified histologically as one of three types: hyperkeratotic, acanthotic, and adenoid. The most common histopathologic features are hyperkeratosis, acanthosis, and papillomatosis. (4)

Most seborrheic keratoses can be diagnosed by simple examination. (2) A larger pigmented lesion or one that has an atypical appearance should be biopsied preoperatively and differentiated from an ordinary nevus, a pigmented basal cell carcinoma, a nodular melanoma, and other neoplasms and skin lesions." (1,2,4) A seborrheic keratosis can also be confused with a squamous cell carcinoma, especially when inflammation alters the histologic appearance by causing maturation of the keratinocytes and increasing mitosis. (5)

It has been reported that the coexistence of basal or squamous cell carcinomas with seborrheic keratoses, although rare, is possible; such a possibility should be considered when a lesion undergoes an unusual or abrupt change in size or color. (6,7)

Removal is advised for lesions that are cosmetically unpleasant or chronically pruritic. (1,8,9) Among the acceptable methods of removal are curettage followed by light electrocauterization of the base, liquid nitrogen application, carbon dioxide laser vaporization, and electrosurgery. (1,4,9) Although excisional surgery is not usually indicated for seborrheic keratosis, shave excision is the treatment of choice when a histologic confirmation of free margins is desired. (1)

Finally, it has been reported that a sudden eruption of numerous pruritic seborrheic keratoses in an adult (LeserTrelat sign) is a sign of internal malignancy. (10) This phenomenon is considered to be a paraneoplasmatic disorder.

From the Department of Otolaryngology, Venizelion Hospital (Dr. Kyrmizakis, Dr. Vrentzos, and Dr. Amanakis), the Department of Otolaryngology, University Hospital (Dr. Papadakis and Dr. Bizakis), and the Department of Pathology, Venizelion Hospital (Dr. Chroniaris), Heraklion, Crete, Greece.

Reprint requests: Dionysios E. Kyrmizakis, MD, DDS, 25 Papanastasiou St., Heraklion, Crete 71306, Greece. Phone: +30-81-324-356; fax: +30-81-324-356; e-mail: dkyrmiz@yahoo.com

References

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(2.) Pariser RJ. Benign neoplasms of the skin. Med Clin North Am 1998;82:1285-307.

(3.) Boies LR, Jr. Diseases of the external ear. In: Adams GL, Boies LR, Jr., Hilger PA, eds. Boies Fundamentals of Otolaryngology: A Textbook of Ear, Nose, and Throat Diseases, 6th ed. Philadelphia: W.B. Saunders, 1989:77-89.

(4.) Mirowski GW, Rozycki TW. Common skin lesions. In: Regezi JA, Sciubba JJ, eds. Oral Pathology: Clinical Pathologic Correlations. 3rd ed. Philadelphia: W.B. Saunders, 1999:479-517.

(5.) Lambert PR, Fechner RE, Hatcher CP. Seborrheic keratosis of the ear canal. Otolaryngol Head Neck Surg 1987;96:198-201.

(6.) Akasaka T, Kon S. Two cases of basal cell carcinoma arising in seborrheic keratosis. J Dermatol 1997;24:322-7.

(7.) Anderson PJ, Zuk JA, Rao GS, Berry RB. Squamous cell carcinoma arising within seborrheic keratosis. Plast Reconstr Surg 1998; 102:453-5.

(8.) DiBartolomeo JR, Paparella MM, Meyerhoff WL. Cysts and tumors of the external ear. In: Paparella MM, Shumrick DA, Gluckman JL, Meyerhoff WL, eds. Otolaryngology. 3rd ed., vol. 2. Philadelphia: W.B. Saunders, 199 1:1243-58.

(9.) Saporta D, Rothfeld ID. Pathologic quiz case 1. Seborrheic keratosis, irritated type. Arch Otolaryngol Head Neck Surg 1989; 115:1136-8.

(10.) Schwartz RA. Sign of Leser-Trelat. J Am Acad Dermatol 1996; 35:88-95.

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